Don't use unsafe convenience mode for verifying detached OpenPGP signatures.

It's going away for good reasons: https://bugs.debian.org/771992
Clarify how to check PO files.
Add December meeting minutes.
Import new translations.
Add anchor
updated PO files
Create a CA bundle for Tails Upgrader at ISO build time.

This bundle contains both the CA that signed the current certificate,
and the one that will sign the next one.
Add alpha channel incremental upgrade path from 1.2.1 to 1.2.2.

This will ease testing of the 1.2.1_to_1.2.2 IUK, for the 1.2.2
emergency release.
Fix UDF target-files' paths.
will-fix: #8141 add details on repositories, add 1 glossary, what can be translated
will-fix: #8141 correct url. make this more readable.
will-fix: #8141 put contributors to the end of the page
Tails doesn't encrypt by default... except in persistence (#7357)
Simplify
Use consistent terminology
Merge branch 'doc/7357-warnings_persistence_encrypted'
updated PO files
FAQ: Can I help the Tor network by running a Relay or a Bridge with Tails? (#6872)
Use consistent typography
Use consistent terminology