8.5
docs: Rename "private message" -> "direct message".
docs: Update Ruff badge and links.
docs: Add section about mentioning others to commit discipline doc.
docs: Fix typo on Design discussions doc.
docs: Add a guide on suggesting features and improvements.
docs: Add contributor guide page on licensing.
docs: Adjust wording and phrasing for clarity.
docs: Clarify where labels are noted.
docs: Link to new PR review process doc from /contributing/reviewable-prs.md.
docs: Fix many spelling mistakes.