Rename rustc -> rustc_middle in doc links

Author: flip1995

CONTRIBUTING.md

@@ -70,7 +70,7 @@ an AST expression). `match_def_path()` in Clippy's `utils` module can also be us
 [`T-AST`]: https://github.com/rust-lang/rust-clippy/labels/T-AST
 [`T-middle`]: https://github.com/rust-lang/rust-clippy/labels/T-middle
 [`E-medium`]: https://github.com/rust-lang/rust-clippy/labels/E-medium
-[`ty`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/ty
+[`ty`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty
 [nodes in the AST docs]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_ast/ast/
 [deep-nesting]: https://github.com/rust-lang/rust-clippy/blob/557f6848bd5b7183f55c1e1522a326e9e1df6030/clippy_lints/src/mem_forget.rs#L29-L43
 [if_chain]: https://docs.rs/if_chain/*/if_chain

doc/adding_lints.md

@@ -463,11 +463,11 @@ don't hesitate to ask on [Discord] or in the issue/PR.
 [utils]: https://github.com/rust-lang/rust-clippy/blob/master/clippy_lints/src/utils/mod.rs
 [if_chain]: https://docs.rs/if_chain/*/if_chain/
 [from_expansion]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/struct.Span.html#method.from_expansion
-[in_external_macro]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/lint/fn.in_external_macro.html
+[in_external_macro]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/lint/fn.in_external_macro.html
 [span]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/struct.Span.html
 [applicability]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_errors/enum.Applicability.html
 [rustc-dev-guide]: https://rustc-dev-guide.rust-lang.org/
-[nightly_docs]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/
+[nightly_docs]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/
 [ast]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_ast/ast/index.html
-[ty]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/ty/sty/index.html
+[ty]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/sty/index.html
 [Discord]: https://discord.gg/rust-lang