Move them into new `error_codes.rs` tidy check.

Co-authored-by: Bruno Kolenbrander <[email protected]>

Co-authored-by: bjorn3 <[email protected]>

…nt-have-docs, r=jyn514

Add some docs to `bug`, `span_bug` and `delay_span_bug`

cc `@mejrs` as you wanted me to do this, does this look good and understandable?

…check, r=mejrs,klensy,GuillaumeGomez

refactor: clean up `errors.rs` and `error_codes_check.rs`

`errors.rs` is basically unused now, `error_codes_check.rs` is useful but not well commented, etc. It also doesn't check certain things which are certainly not correct. For example, `E0505` has a UI test in `src/test/ui/error-codes/` but that test actually outputs `E0504`?! Other issues like these exist. I've implemented these with "warnings" which are a bit rough around the edges but should be removed eventually.

r? `@GuillaumeGomez` (again not sure if you want to review but its relevant to you)

Improve include macro documentation

As outlined in rust-lang#106118, the `include!` macro is a SEO problem when it comes to the Rust documentation. Beginners may see it as a replacement to `include` syntax in other languages. I feel like this documentation should quite explicitly link to the modules' documentation.

The primary goal of this PR is to address that issue by adding a warning to the documentation. While I was here, I also added some other parts. This included a `Uses` section and some (intra doc) links to other relevant topics.

I hope this can help beginners to Rust more quickly understand some multi-file project intricacies.

# References
- Syntax for the warning: https://github.com/tokio-rs/tracing/blob/58accc6da3f04af3f6144fbe6d68af7225c70c02/tracing/src/lib.rs#L55

…otriddle

Fix rustdoc source code rendering for `#[path = "../path/to/mod.rs"]` links

Fixes rust-lang#103517

While generating the location for modules source HTML to be saved at, a `..` path component appeared to be translated to `/up/`.
Additionally, while generating the navigation sidebar, `..` path components were ignored. This means that (as in the issue above), a *real* directory structure of:
```
sys/
  unix/
    mod.rs  <-- contains #![path = "../unix/mod.rs]
    cmath.rs
```
was rendered as:
```
sys/
  unix/
    mod.rs
    unix/
      cmath.rs  <-- links to sys/unix/unix/cmath.rs.html, 404
```
While the *files* were stored as
```
sys/
  unix/
    mod.rs.html
    up/
      unix/
        cmath.rs.html
```

Tiny formatting fix

…riddle

rustdoc-gui: Use new block syntax for define-function in goml scripts

r? `@notriddle`

Add default and latest stable edition to --edition in rustc (attempt 2)

Fixes rust-lang#106041

No longer leaks string like my first attempt PR, rust-lang#106094 - uses LazyLock to construct a `&'static str`

It will now output the default edition and latest stable edition in the help message for the `--edition` flag.

Going to request the same reviewer as the first attempt for continuity - r? `@Nilstrieb`