Improve Debian compatibility docs

TODO items for next privacy policy update

Update build compatibility matrix for Alpine 3.11

builds.sr.ht/manifest.md: use "compatibility page"

Alternating between "compatibility page" and "compatibility list"
suggests the links point to different resources

builds.sr.ht/manifest.md: document "arch"

Update F31, add F32 to builds.sr.ht image compatibility page

builds.sr.ht: document new environment variables

Link to build shell doc from builds index

Remove Fedora 29 from compatibility.md

End of life

Fix a typo in the build secrets tutorial: s/every/ever/

Remove obsolete warning from git.sr.ht docs

Update builds.sr.ht/index.md

Document OpenBSD 6.6

Fix a typo in hg.sr.ht's email doc

Suggest a better "flagtemplate" for hg email

Add GET /api/jobs to builds.sr.ht/api.md

Remove Ubuntu Xenial from compat list

minor edit to make example more explicit

Update nixos/latest to 19.09

Fix typo in document paste:create OAuth scope