Rollup merge of #142082 - xizheyin:rustc_attr_data_structures, r=jdonszelmann

Refactor `rustc_attr_data_structures` documentation

I was reading through `AttributeKind` and realized that attributes like `InlineAttr` didn't appear in it, however, I found them in `rustc_codegen_ssa` and understood why (guessing).

There's almost no overall documentation for this crate, I've added the organized documentation at the top of `lib.rs`, and I've grouped the Attributes into two categories: `AttributeKind` that run all through the compiler, and the ones that are only used in `codegen_ssa`, such as `InlineAttr`, `OptimizeAttr`, `InstructionSetAttr`.

Also, I've added documentation for `AttributeKind` that further explains why attributes like `InlineAttr` don't appear in it, with examples for each variant.

r? ```@jdonszelmann```

0 files changed, 0 insertions, 0 deletions