1. Improve display of enum flags. Thanks @mikernet! (#7043)
2. Some improvements in docfx.console.targets. Thanks @alexrp! (#7117)
3. New tools available: TocDocfxCreation, DocLinkChecker, DocLanguageTranslator and some examples. Thanks @Ellerbach! (#7231)
4. Security updates:
   1. Replace use of MD5, SHA1 with SHA256. (#7149, #7157)
   2. Specify noopener/noreferer for external link. (#7204)
   3. Avoid reinterpreting DOM text as HTML without escaping meta-characters. (#7210)
   4. Check certificate revocation list in HTTP calls. (#7142)
   5. Upgrade some NPM, NuGet packages. (#7135, #7147)
   6. Migrate bower to NPM. (#7273)
   7. Enable CodeQL. (#7184)
5. Bug fix:
   1. <code source=...> not work when using DLL + XML documents as input. Thanks @james-hunt-ra! (#7096)
   2. Sub navbar not fully shows if remove .html extension from URL. Thanks @CyberAndrii! (#7046)