9.2
docs: Update `docs/contributing/` files to use channel.
docs: Add comma to all uses of "e.g." in contributor docs.
docs: Update Black and isort references to Ruff.
contributor docs: Tweak wording in "Counting contributions" intro.
docs: Mobile UI design is discussed in #mobile, not #mobile-team.
documentation: Revise uses of "e.g.," followed by a colon.
contributor docs: Improve article on submitting a pull request.
docs: Add contributor guide page on licensing.
docs: Update CZO links from stream to channel in docs and comments.
contributor docs: Reorganize content on pull request docs.
docs: Fix a couple typos in pull request guide.
docs: Fix many spelling mistakes.