toolchain -> rustup-toolchain

Author: RalfJung

CONTRIBUTING.md

@@ -23,7 +23,7 @@ tested against. Other versions will likely not work. After installing
 [`rustup-toolchain-install-master`], you can run the following command to
 install that exact version of rustc as a toolchain:
 ```
-./toolchain
+./rustup-toolchain
 ```
 
 [`rustup-toolchain-install-master`]: https://github.com/kennytm/rustup-toolchain-install-master
@@ -38,7 +38,7 @@ needed.
 
 To update the `rustc-version` file and install the latest rustc, you can run:
 ```
-./toolchain HEAD
+./rustup-toolchain HEAD
 ```
 
 Now try `./miri test`, and submit a PR once that works again.

toolchain renamed to rustup-toolchain

@@ -7,11 +7,11 @@ set -e
 #
 # USAGE:
 #
-# ./toolchain: Update "miri" toolchain to match `rust-version` (the known-good version for this commit).
+# ./rustup-toolchain: Update "miri" toolchain to match `rust-version` (the known-good version for this commit).
 # 
-# ./toolchain HEAD: Update "miri" toolchain and `rust-version` file to latest rustc HEAD.
+# ./rustup-toolchain HEAD: Update "miri" toolchain and `rust-version` file to latest rustc HEAD.
 # 
-# ./toolchain $COMMIT: Update "miri" toolchain and `rust-version` file to match that commit.
+# ./rustup-toolchain $COMMIT: Update "miri" toolchain and `rust-version` file to match that commit.
 
 # Determine new commit.
 if [[ "$1" == "" ]]; then