Add occ maintenance:repair-share-owner to the docs

[pReya]

The command occ maintenance:repair-share-owner is not part of the documentation: https://docs.nextcloud.com/server/latest/admin_manual/configuration_server/occ_command.html#maintenance-commands

It was introduced in this PR: nextcloud/server#32211 – yet there was no documentation in this PR.

Would be really nice, if someone (who knows what it does) could document it (@artonge maybe?)

[artonge]

In some cases, when moving a share around, its owner can fell out of sync, which breaks some features like transfer ownership.

The root cause was fixed in nextcloud/server#31728.
Then we introduced occ maintenance:repair-share-owner to fix already broken shares.

[artonge]

@pReya Not sure if there is much more to it. If you feel like adding the documentation for it, then thank you, else I'll do it in a few days :)

[artonge]

A few days later: #12132