Dereferenced links

Author: Eric Findlay

how_to_contribute.md

@@ -19,19 +19,17 @@ Writing tests and documentation is how many people get started and is
 really useful. There are links to these kind of issues too. Likewise
 finding bugs and filing issues in any of the projects linked here is
 very much appreciated. As a reminder, all contributors are expected to
-follow our [Code of Conduct](https://www.rust-lang.org/conduct.html).
+follow our [Code of Conduct][coc].
+
+[coc]: https://www.rust-lang.org/conduct.html
 
 ## Finding Something to Work On
 
 #### Issues
 
-If you're looking for
-[issues](https://github.com/rust-lang/rust/issues) on the Rust repo
-and want something easy-ish to start with, look for the
-[E-easy](https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AE-easy)
-or
-[E-mentor](https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AE-easy+label%3AE-mentor)
-labels.
+If you're looking for [issues][rust_issues] on the Rust repo
+and want something easy-ish to start with, look for the [E-easy][e_easy_issues]
+or [E-mentor][e_mentor_issues] labels.
 
 Contributors with sufficient permissions on the Rust repo can help by
 adding labels to triage issues:
@@ -53,50 +51,63 @@ I-nominated label.
 - **Purple** metabug labels mark lists of bugs collected by other
   categories.
 
+[rust_issues]: https://github.com/rust-lang/rust/issues
+[e_easy_issues]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AE-easy
+[e_mentor_issues]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AE-easy+label%3AE-mentor
+
 #### The Rust compiler
 
-The compiler is part of the [main repo](https://github.com/rust-lang),
-which also includes the standard library crates and a whole bunch of
-supporting code. For questions about the compiler, there is the
-[#rustc](irc://moznet/rustc) IRC channel. Compiler errors (ICE for
-'internal compiler errors') can be searched for in issues using the
-[I-ICE](https://github.com/rust-lang/rust/labels/I-ICE) label. These
-are usually good bugs to start with because it's easy to know when
-you've fixed them, and they're often relatively self-contained. If
-you're interested in parsing, macros, syntactic stuff, the
-[parsing](https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AA-parser)
-label and the
-[macro](https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AA-parser+label%3AA-macros)
-label are a good places to start.
+The compiler is part of the [main repo][main_repo], which also
+includes the standard library crates and a whole bunch of supporting
+code. For questions about the compiler, there is the
+[#rustc][rustc_irc] IRC channel. Compiler errors (ICE for 'internal
+compiler errors') can be searched for in issues using the
+[I-ICE][i_ice_issues] label. These are usually good bugs to start with
+because it's easy to know when you've fixed them, and they're often
+relatively self-contained. If you're interested in parsing, macros,
+syntactic stuff, the [parsing][parsing_issues] label and the
+[macro][macro_issues] label are a good places to start.
+
+[main_repo]: https://github.com/rust-lang
+[rust_irc]: irc://moznet/rustc
+[i_ice_issues]: https://github.com/rust-lang/rust/labels/I-ICE
+[parsing_issues]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AA-parser
+[macro_issues]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AA-parser+label%3AA-macros
 
 #### Standard Libraries
 
-[Libstd](https://github.com/rust-lang/rust/tree/master/src/libstd),
-[libcollections](https://github.com/rust-lang/rust/tree/master/src/libcollections),
-[liballoc](https://github.com/rust-lang/rust/tree/master/src/liballoc)
-and
-[libcore](https://github.com/rust-lang/rust/tree/master/src/libcore)
-are the main library crates.  These all appear to users as if they are
-part of libstd, the standard library. These tend to be very
-fundamental libraries - built-in types, low level IO and concurrency,
-allocation, essential collections, and so forth. You should join
-[#rust-libs](irc://moznet/rust-libs) if you are interested in contributing
-to the Rust libraries.
+[Libstd][libstd], [libcollections][libcollections],
+[liballoc][liballoc] and [libcore][libcore] are the main library
+crates.  These all appear to users as if they are part of libstd, the
+standard library. These tend to be very fundamental libraries -
+built-in types, low level IO and concurrency, allocation, essential
+collections, and so forth. You should join [#rust-libs][libs_irc] if
+you are interested in contributing to the Rust libraries.
+
+[libstd]: https://github.com/rust-lang/rust/tree/master/src/libstd
+[libcollections]: https://github.com/rust-lang/rust/tree/master/src/libcollections
+[liballoc]: https://github.com/rust-lang/rust/tree/master/src/liballoc
+[libcore]: https://github.com/rust-lang/rust/tree/master/src/libcore
+[libs_irc]: irc://moznet/rust-libs
 
 #### Cargo
 
-[Cargo](https://github.com/rust-lang/cargo/issues) is Rust's package manager.
+[Cargo][cargo_issues] is Rust's package manager.
+
+[cargo_issues]: https://github.com/rust-lang/cargo/issues
 
 #### Tests
 
 Contributing tests is extremely valuable to the Rust project. For the
 compiler and standard libraries, there are unit tests (usually)
 embedded in the source code and regression tests in the
-[src/tests](https://github.com/rust-lang/rust/tree/master/src/test)
-directory. There is a list of issues which have (probably) been fixed,
-but still need a test. Nearly any other project will be extremely
-welcoming of new tests too.  Writing test cases is a great way to
-begin to understand a new project and get started contributing.
+[src/tests][tests] directory. There is a list of issues which have
+(probably) been fixed, but still need a test. Nearly any other project
+will be extremely welcoming of new tests too.  Writing test cases is a
+great way to begin to understand a new project and get started
+contributing.
+
+[test]: https://github.com/rust-lang/rust/tree/master/src/test
 
 #### Checking Older Bugs
 
@@ -105,9 +116,10 @@ fixed. And sometimes, the original bug may go stale because something
 has changed in the meantime. It can be helpful to go through older bug
 reports and make sure that they are still valid. Load up an older
 issue, double check that it's still true, and leave a comment letting
-us know if it is or is not. The [least recently
-updated](https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-asc)
-sort is good for finding issues like this.
+us know if it is or is not. The [least recently updated][lru_issues]
+sort is good for finding issues like this.  
+
+[lru_issues]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-asc
 
 #### Documentation
 
@@ -117,16 +129,17 @@ projects. Many aspects of the docs don't require super-deep knowledge,
 especially if they're aimed at newcomers. It's also a great way to
 learn more about the language or specific libraries.
 
-- [The
-  Book](https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AA-book)
-The main guide to learning Rust.
-- [Rust
-  Documentation](https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AA-docs)
-- [Rust by Example](https://github.com/rust-lang/rust-by-example/issues)
-- [Rust for C++
-  Programmers](https://github.com/nrc/r4cppp/issues) A tutorial aimed
+- [The Book][rustbook_issues] The main guide to learning Rust.
+- [Rust Documentation][rustdoc_issues]
+- [Rust by Example][rust_by_example_issues]
+- [Rust for C++ Programmers][rust_for_cpp_issues] A tutorial aimed
 at experienced C++ programmers coming to Rust.
 
+[rustbook_issues]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AA-book
+[rustdoc_issues]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AA-docs
+[rust_by_example_issues]: https://github.com/rust-lang/rust-by-example/issues
+[rust_for_cpp_issues]: https://github.com/nrc/r4cppp/issues
+
 #### Tools
 
 Tools play a huge part in the success of a language. Rust has some
@@ -144,15 +157,21 @@ management, but we need much more.
 
 #### Other Contributions
 
-Try [Github Trending](https://github.com/trending?l=rust) for
-currently active Rust projects. There are a number of other ways to
-contribute to Rust that don't deal directly with the Rust repository.
-
-- Answer questions in [#rust](irc://moznet/rust), on the [Rust
-  Forum](https://users.rust-lang.org/) or on [Stack
-Overflow](http://stackoverflow.com/questions/tagged/rust).
-- Participate in the [RFC process](https://github.com/rust-lang/rfcs).
-- Find a [requested community
-library](https://github.com/rust-lang/rfcs/labels/A-community-library)
-, build it, and publish it to [Crates.io](http://crates.io). Easier
-said than done, but very, very valuable!
+Try [Github Trending][trending] for currently active Rust projects.
+There are a number of other ways to contribute to Rust that don't deal
+directly with the Rust repository.
+
+- Answer questions in [#rust][rust_irc], on the [Rust Forum][forum] or
+  on [Stack Overflow][stack_overflow].
+- Participate in the [RFC process][rfcs].
+- Find a [requested community library][requested], build it, and
+  publish it to [Crates.io][crates]. Easier said than done,
+but very, very valuable!
+
+[trending]: https://github.com/trending?l=rust
+[rust_irc]: irc://moznet/rust
+[forum]: https://users.rust-lang.org/
+[stack_overflow]: http://stackoverflow.com/questions/tagged/rust
+[rfcs]: https://github.com/rust-lang/rfcs
+[requested]: https://github.com/rust-lang/rfcs/labels/A-community-library
+[crates]: http://crates.io