15.8.0

What's Changed

• Search: optimize queryset when searching for subprojects by @stsewd in #12588
• Raise clear error when mkdocs.yml config file is missing by @humitos in #12521
• Make doctool page titles better for SEO by @ericholscher in #12603
• Replace wrong usage of prefetch_related with select_related by @stsewd in #12602
• Docs: add mystmd to the list of supported doctools by @Copilot in #12608
• Docs: add Zensical documentation to doctools by @humitos in #12606
• Save last login method in a cookie by @humitos in #12286
• Docs: document --backupdb argument for inv docker.manage by @nikblanchet in #12617
• Tasks: remove user_pk from task calls by @stsewd in #12610
• Project: don't ask to recreate project if SSH key wasn't added by @stsewd in #12609
• Build: better support for empty default branch by @stsewd in #12462

Full Changelog: 15.7.0...15.8.0