rustdoc: Tracking issue for lint `rustdoc::missing_doc_code_examples`

[Nemo157]

This is a tracking issue for the lint rustdoc::missing_doc_code_examples.
The feature gate for the issue is #![feature(rustdoc_missing_doc_code_examples)].

About tracking issues

Tracking issues are used to record the overall progress of implementation.
They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.

Steps

• Implement the lint [rustdoc] Add lint for doc without codeblocks #54349
• Adjust documentation (see instructions on rustc-dev-guide)
• Stabilization PR (see instructions on rustc-dev-guide)

Unresolved Questions

• Rustdoc lints don't fire for pub re-exports #77230
• rustdoc::missing_doc_code_examples inconsistent with Rust API Guidelines #87858

Implementation history

• [rustdoc] Add lint for doc without codeblocks #54349
• Separate missing_doc_code_examples from intra-doc links #74855
• Missing doc examples lint improvements #75776
• Document lint missing_doc_code_examples is nightly-only #76212
• Don't warn for missing_doc_examples when item is #[doc(hidden)] #76716
• Make rustdoc lints a tool lint instead of built-in #80527
• Don't lint about missing code examples in derived traits #88735
• Allow missing code examples in trait impls. #88745
• Add test to ensure that the missing_doc_code_examples is not triggered on foreign trait implementations #90098

[jplatte]

When this lands, could there be a new lint group like rustdoc::all that activates all non-"restriction" rustdoc lints? All the current lints in from https://doc.rust-lang.org/rustdoc/lints.html are very useful to deny in CI, but this one obviously isn't (for most people).

[peter-lyons-kehl]

Please add #109592 and its PR (if accepted), and #109601.

[peter-lyons-kehl]

@jplatte FYI related to rustdoc::all

• rustdoc::missing_doc_code_examples inconsistent with Rust API Guidelines #87858, and
• rustdoc::all in src/librustdoc/lint.rs -> register_lints(...): https://github.com/rust-lang/rust/blob/master/src/librustdoc/lint.rs#L195.