People had a hard time spotting it during the user testing.

During the user testing, everybody who looked for it had a hard time
finding it or even gave up.

- Replace TrueCrypt documentation on the command line.
- Adjust LUKS documentation to explain the alternative with VeraCrypt.

This reverts commit c707d4f1.

I'll write the documentation without auto-mounting until we have a
decision on #15628.

Merge remote-tracking branch 'segfault/bugfix/15636-screen-locker-unicode' into stable (Fix-committed: #15636)

Merge remote-tracking branch 'segfault/feature/14481-TCRYPT-support-beta' into feature/14481-TCRYPT-support-beta

The /etc/xdg/gnome-mimeapps.list is created (and overwritten)
by chroot_local_hooks/10-tbb, so we append the required line in a hook.

Merge branch 'feature/15575-open-doc-instead-of-getting-started' into stable (Fix-committed: #15575)

The "Getting started" page had a 'Found a bug?' heading but the "Documentation"
page has no such thing.

The changed string is not translatable so all languages get the English version.

- /getting_started is very old and needs a serious lifting.

- During the user testing of the Additional Software beta, 3 out of 5
  participants ended up on this page. None of them read it. 2 used it to reach
  /doc which is what they were looking for. 1 got lost and ended up on /design.