I got bit by this and tried to send to `?channel=#tpo-admin`, which
obviously fails because # is a special character. Easier to just skip
the pound sign altogether.

It's where I looked for it first, and the gitlab page is waay to
long. We keep a pointer anyways, so that people can find it in both places.

Seems like this may fix tpo/tpa/team#40376

Stumbled upon this in
tpo/tpa/team#31350

here we explain the command we'll run on a separate line for those
diagonal-readers.

The rationale here is that's already available at the head of the
Python script, and was actually not directly tested recently. I only
put this together from memory (well, git history and guesses) so it
might actually not work at all. It's mostly pseudo-code, and shouldn't
be ran directly.

Instead, explain generally, with words, what the script does.

We keep the pager / disaster stuff at the end of the section so it's
easier to find.

See tpo/tpa/gitlab#97

See gitlab#66 (comment 2725214)

This is really about trac more than gitlab, after all. Now that we
migrated, those docs are not really useful anymore and can be archived
to that other page.

We desperately need linting here.. :(