Some minor documentation issues and suggestions:

• Issues
  • README.md: The chapters in the Documentation section weren't updated after merging 📚 docs: split usage guide into tutorial, how-to, and reference #441; alternatively, the chapters could also simply be removed, a link to https://platformdirs.readthedocs.io is sufficient IMHO (already mentioned in 📚 docs: split usage guide into tutorial, how-to, and reference #441 (comment))
  • docs/api.rst: Documentation of site_applications_dir (✨ feat(api): add site_applications_dir property #442) is missing
  • docs/api.rst: Documentation of site_bin_dir (✨ feat(api): add site_bin_dir property #443) is missing
  • docs/platforms.rst: Remove the "Environment variable overrides" headline below the "Windows" section (this sub-section otherwise also includes e.g. the class docs, IMHO the sub-section headline simply isn't necessary, there's none for Unix either)
• Suggestions
  • docs/api.rst: Unify headlines (e.g., "User data directory" for user_data_dir vs. just "Cache directory" for user_cache_dir, IMHO should be "User cache directory" et. al.)
  • docs/api.rst: Move user_runtime_dir, user_applications_dir, and user_bin_dir in front of user_documents_dir et. al. to not disrupt the shared order with the site_*_dir method list
  • docs/platforms.rst: Group the user_*_dir methods into a "User directories" section, and the site_*_dir methods into a "Shared directories" section, matching docs/api.rst; also use the same method order as docs/api.rst
  • docs/api.rst and docs/platforms.rst: Maybe add reference links to the matching section of the same method to both pages (e.g., add a link to platforms.html#user-cache-dir in the user_cache_dir section of docs/api.rst, and vice-versa)
  • docs/parameters.rst: The XDG_* env variables are explained in a section there, but not the WIN_PD_OVERRIDE_* env variables; make sure not to create too many redundancies with the existing class docs in docs/api.rst, the sections - also including the "Windows" -> "Environment variable overrides" section in docs/howto.rst - should rather reference and link to each other
  • docs/howto.rst and docs/parameters.rst: There's some redundancy between the "Linux / Unix" -> "XDG Base Directory Specification" section of docs/howto.rst, the "XDG environment variables" section of docs/parameters.rst, and the class docs in docs/api.rst; some redundancies are expected and feasible, but IMHO not to this extent; the sections should rather reference and link to each other
• Other
  • Do the PLATFORMDIRS_* env variables actually still exist? I'm not entirely sure, but I guess not? Because they are still mentioned in docs/howto.rst, but nowhere else. If they were never actually released, they should also be removed from the changelog.