Write standard diagnostic documentation for v5 core lints

[parlough]

The following are now core or recommended lints and should be prioritized for diagnostic style documentation:

• [ ] library_annotations
• [ ] unnecessary_library_name
• [ ] unintended_html_in_doc_comment
• [ ] invalid_runtime_check_with_js_interop_types

The following is another good candidate due to previously being a warning and being relatively straightforward:

• [ ] use_truncating_division