GitLab

This was the user scenario pointed out during the April 3rd meeting to
rescue the old OpenPGP verification instructions. It also makes sense as
the only reason left behind having a direct download.

The old verification instructions will be moved here.

Rescue the translations we had from this into doc.*.po. The PO plugin
will do something smart with it.

As we sometimes us the FAQ to store frequent concerns before migrating
it to the doc, it deserves a bit more of visibility.

Wikipedia recommends to only use ampersand where space is limited:

https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style#Ampersand

Since this section points directly and only to the download page, let's
call it in a similar way.

As started with efe9ecf.

This reverts commit 5a9c39a6.

This reverts commit 848dd103, reversing
changes made to 932a867d.

This reverts commit 8a39f529.

Remove the 'Use Tails' categories and create new ones:

- First steps with Tails
- Connect to the Internet anonymously
- Encryption & privacy
- Work on sensitive documents
- Advanced topics

Each one corresponds to a topic specific intro page, eg. first_steps.mdwn, and a
category index, first_steps.index.mdwn, which is in turn inlined in doc.mdwn and
first_steps.mdwn to avoid duplication.

This is mainly renoving numbers in page names