homectl: add page

[navarroaxel]

• The page (if new), does not already exist in the repo.
• The page is in the correct platform directory (common/, linux/, etc.)
• The page has 8 or fewer examples.
• The PR title conforms to the recommended templates.
• The page follows the content guidelines.
• The page description includes a link to documentation or a homepage (if applicable).

[bl-ue]

Looks like https://wiki.archlinux.org/index.php/Systemd-homed#userdbctl could use a page too 🤔

[Waples]

lgtm

[sbrl]

Thanks for the new page, @navarroaxel! Just a few minor comments.

In general systemd homed looks very concerning indeed in that it performs a number of functions it really shouldn't - I'd suggest that this command is falsely named in that it's more of a user account management command as opposed to a home directory management command.

Regardless, documenting it is a valuable exercise as it ensures those who are unlucky enough to find themselves on the receiving end of a system with systemd-homed installed are able to quickly understand how to administrate the system.