Link to docs referenced from Driver.md (#19420)

Author: kastiglione

docs/Driver.md

@@ -14,9 +14,10 @@ The target audience for this document is people who want to integrate the Swift
 compiler into their build system, rather than using Xcode or the package
 manager (`swift build`). If you're looking to work on the driver itself...well,
 this is probably still useful to you, but you should also check out
-DriverInternals.rst and maybe DependencyAnalysis.rst as well. If you're just
-using Xcode or SwiftPM and want to find out what mysterious command-line
-options you could be passing, `swiftc --help` is a better choice.
+[DriverInternals.rst](DriverInternals.rst) and maybe
+[DependencyAnalysis.rst](DependencyAnalysis.rst) as well. If you're just using
+Xcode or SwiftPM and want to find out what mysterious command-line options you
+could be passing, `swiftc --help` is a better choice.
 
 If you're invoking `swift -frontend` directly, and you aren't working on the
 compiler itself...well, this document should convince you to not do that.
@@ -25,8 +26,8 @@ Some terms:
 
 - For the purposes of this document, a _module_ is a single distributable unit
   of API. (We use this term for a lot of other things too, though; check out
-  Lexicon.rst for the full list.) "Foundation" is a single module, as is the
-  Swift standard library ("Swift"). An app is a module too.
+  [Lexicon.rst](Lexicon.rst) for the full list.) "Foundation" is a single
+  module, as is the Swift standard library ("Swift"). An app is a module too.
 
 - A _compilation unit_ is a set of source files that are compiled together. In
   Swift, everything intended to be in the same module must be part of the same
@@ -205,13 +206,13 @@ in becoming more like non-whole-module builds.
 ## Incremental Builds ##
 
 Incremental builds in Swift work by primarily by cross-file dependency
-analysis, described in DependencyAnalysis.rst. Compiling a single file might be
-necessary because that file has changed, but it could also be because that file
-depends on something else that might have changed. From a build system
-perspective, the files in a particular module can't be extracted from each
-other; a top-level invocation of the compiler will result in a valid
-compilation of the entire module, but manually recompiling certain files is not
-guaranteed to do anything sensible.
+analysis, described in [DependencyAnalysis.rst](DependencyAnalysis.rst).
+Compiling a single file might be necessary because that file has changed, but
+it could also be because that file depends on something else that might have
+changed. From a build system perspective, the files in a particular module
+can't be extracted from each other; a top-level invocation of the compiler will
+result in a valid compilation of the entire module, but manually recompiling
+certain files is not guaranteed to do anything sensible.
 
 Performing an incremental build is easy; just pass `-incremental` and be sure to
 put "swift-dependencies" entries in your output file map.