We stop short of rewriting all playbooks for Prometheus, and instead
add references to the task of adding playbooks for
everything (prometheus-alerts#16) where we found references to
nagios.

I forgot to change it after the copy/paste

also add a wildcard to the suggested find command so that it matches
things like `hostname.torproject.org.yaml`

also show an example to query by parameter value

This is the most likely scenario so it should appear first in the
documentation.

I've also modified the example command for running non-ganeti reboots so
that it directly launches the reboots and it automatically excludes
ganeti nodes.

the options were renamed to include the unit type (e.g. minutes or
seconds)

If I just copy/paste the examples from this page, I get an error like
this:

    No idea what 'perdulce.torproject.org' is!

This is because the last sed command in subshells that fetch information
is not doing what it should since output is separated by newlines
instead of spaces. With `paste` we can make this work better.

Adding an explicit token name makes it easier for people to find it again.

I feel like this is not complete, but I jotted down what I knew.

The alert was added during phase A of the migration to prometheus but I
had not written anything about how to handle those situations.

This goes with the new alert for this condition.