Retire tech-specific wiki content

See merge request !4

The `README.md` has been updated to point to the new location for this
documentation in the general wiki. A snapshot of the wiki content here
was created using `git bundle` and instructions for using it have been
included in the README.md as well.

Once this commit is merged the existing Wiki pages in this repository
will be deleted.

Consolidation of old infra overview into this page, mass update of formatting...

See merge request !3

Consolidation of old infra overview into this page, mass update of formatting and content for clarity, reorganization.

Fix typo

See merge request !2

Backups are handled elsewhere now

Script ran fine on the console, failed in cron job.  This is because
the docker-compose exec command was attempting (by default) to allocate
 a TTY, and failing.  This was also not being detected because the
default bash behaviour is to return the status of the last command
in a pipe (in this case, gzip). Enable pipefail option to prevent this.

And on runko.social.coop.  Used as a stopgap backup solution there.

A stopgap until we get a proper backup

Copied from the cryptpad version.