message: Fix link to internal rustc documentation
diff: @@ -14,4 +14,4 @@ contribute and provide bug fixes for the compiler.
  [Compiler team]: https://rust-lang.github.io/compiler-team/
  [FIXME page]: https://oli-obk.github.io/fixmeh/
  [Rustc Dev Guide]: https://rustc-dev-guide.rust-lang.org/
  -[internal documentation]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/
  +[internal documentation]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/
  