Rustdoc should error or warn on links that start `#` and recommend `self#` for a module or `Self#` for a type. _Originally posted [here](https://github.com/rust-lang/rust/pull/76497#discussion_r485908548) and [here](https://github.com/rust-lang/rust/pull/76497#discussion_r485968957)._ --- Cc @jyn514 @rustbot modify labels: A-intra-doc-links T-rustdoc