Auto merge of #86849 - jyn514:rustdoc-group, r=Manishearth

Warn when `rustdoc::` group is omitted from lint names

When rustdoc lints were first made a tool lint, they gave an unconditional warning when you used the original name:
```
warning: lint `broken_intra_doc_links` has been renamed to `rustdoc::broken_intra_doc_links`
  --> $DIR/renamed-lint-still-applies.rs:2:9
   |
LL | #![deny(broken_intra_doc_links)]
   |         ^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `rustdoc::broken_intra_doc_links`
   |
   = note: `#[warn(renamed_and_removed_lints)]` on by default
```
That was reverted in https://github.com/rust-lang/rust/pull/83203 because adding `rustdoc::x` lints would cause the code to break on old versions of the compiler (due to https://github.com/rust-lang/rust/issues/66079#issuecomment-788589193, "fixed" in https://github.com/rust-lang/rust/pull/83216 in the sense that you can now opt-in to not breaking on nightly, which is not ideal but `register_tool` is a long way from stabilizing). Since https://github.com/rust-lang/rust/pull/80527 is now on 1.52.0 stable, we can re-enable the warning. For nightly users, they can change immediately and still have their code work on stable; for stable users, they can change their code in 12 weeks and still have it work up to 3 releases back (about 18 weeks). That seems reasonable to me.

r? `@Manishearth` cc `@rust-lang/rustdoc`

0 files changed, 0 insertions, 0 deletions