After informal discussions over IRC, here are some changes:

- We would ideally merge Weblate but this still needs investigation and discussion.
- Let's aim to retire XMPP and its bot
- Some of us think Jenkins should be retired at some point in favor of GitLab CI

Plus:

- Clarify dependencies
- Merge "Web servers"
- Remove repeated "Sysadmin doc" entry

Also shuffle around some services so they better match the proposed terminology.

Closes: gitlab#157

pkern was lacking context when reading this

Closes: team#41827

See team#41827

The new group will be useful to add yet another section about how to
manage silences.

Using the filter bar for creating alerts can help us create more
advanced filters more easily.

otherwise people will think you can just detach it.

The monitoring example for matching on an included class uses the legacy
`roles` module. To make this example live longer, let's get rid of the
example based on the legacy module.

There's currently no example for how we can match on the presence of a
resource type. It's useful to know that the pattern is a bit different
than how matching for classes is done.

The cumin documentation has some more examples for how to make matching
more precise by using expected parameter values on the resource types.
But we can find those out in the cumin doc. As long as we know from our
side that matching on resource types is possible.