add docs how to disconnect or replace a drive

[szaimen]

• Closes Addition to the instructions: If a hard drive has been mounted but is no longer to be permanently connected to the server #141

Adds a new FAQ article that documents what to do when a drive that was mounted to the server should not stay connected permanently - and, on top of that, how to replace a drive with a new one.

Disconnecting a drive

Unplugging is not enough, since the mount was made persistent during the setup. There is one section per drive type, because the leftovers differ:

• Veracrypt data SSD/HDD: the block in veracrypt-automount.sh, the is-drive-connected.sh cronjob, the entries in the permission/snapshot/scrub scripts, plus the SMB-shares, Nextcloud storages and PLEX/Jellyfin libraries
• Unencrypted BTRFS drive (e.g. Movies/TV-Shows): the fstab entry, the permission/snapshot/scrub entries and the PLEX/Jellyfin libraries
• Unencrypted NTFS drive: only the fstab entry and PLEX/Jellyfin, since no snapshot/scrub/permission scripts get created for those
• Bitlocker drive: both fstab lines (dislocker + the loop mount) and optionally purging dislocker
• Backup drive: mostly harmless because of noauto, but the daily/off-shore backup cronjob needs to get disabled

Replacing a drive

The key point in all four replacement sections is to reuse the mountpath of the old drive, so that the SMB-shares, the Nextcloud storages, the PLEX/Jellyfin libraries and the backup scripts keep working without touching their configuration.

The Veracrypt section is separate because the BTRFS Veracrypt/NTFS Veracrypt scripts always format and encrypt - running them again would delete the data that was just copied over - so the automount block gets written by hand there. The Bitlocker section is separate because only one Bitlocker drive can be mounted at a time, so the data has to take a detour.

Notes

• The article carries a warning at the top that it was created with the help of AI and is not fully tested yet, with a pointer to the issues section
• All commands were checked against the scripts in https://github.com/nextcloud/vm
• Also adds a news entry and a cross-link on the three mount pages

Thanks a lot to @LeoHobi for the suggestion!