Bump version to 0.21.0; rework changelog, contributors, and docs

2026-06-29T16:38:01Z

Release: - Bump version to 0.21.0 and regenerate tusb_option.h, library.json, repository.yml, sonar-project.properties, boards.rst, dependencies.rst - Add 0.21.0 release notes and split the changelog into per-release files under docs/info/changelog/ (date out of title, driver/class groups as sub-headings, DCD & HCD section after Device/Host stacks) Contributors: - Credit each release's PR authors in a Contributors section - Drop the curated contributors page; add MAINTAINERS.rst Docs: - Update Code of Conduct to Contributor Covenant 3.0 (keep it in the repo, remove it from the built docs) - Sidebar: add a home entry, rename the group to "Documentation", move Changelog into it, add a GitHub Sponsor button, merge external links, rename FAQ; hide the inline toctree on the landing page - Add the make-release skill and update the AGENTS.md release process Co-Authored-By: Claude Opus 4.8 (1M context)

tinyusb.git/docs/info/code_of_conduct.rst, branch master

Bump version to 0.21.0; rework changelog, contributors, and docs

update doc