DOC: chat-ops

[MarcoGorelli]

xref #38444 (comment)

There are some GitHub Actions workflows which can be triggered via comments:

1. If you comment @github-actions pre-commit on a pull request, it will trigger a workflow which will autofix formatting errors (e.g. from black or isort)
2. @meeseeksdev backport will trigger a workflow which will backport a given change to a branch (e.g. @meeseeksdev backport 1.2.x)
3. If you comment take on an issue, it will trigger a workflow which will assign the issue to you

These should be documented somewhere in the docs - I think doc/source/development/contributing.rst might be a sensible location. take is already documented in there, but the other two aren't

[1nF0rmed]

Hey, I would like to work on this

[MarcoGorelli]

sure, if you comment take it'll be assigned to you (but I've done it now)