Addition to Time Machine documentation

[y-lee]

In https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/apple-time-machine/ , in the "Connect from macOS" section, I suggest adding:

9. If using an existing Time Machine backup as target, and Time Machine says "Backup Not Completed / The backup on "unraidserver" is already in use" after attempting the first backup to it, reboot the Mac to ensure that the Mac does not have the Time Machine backup mounted somewhere already. After the reboot, manually start another Time Machine backup or wait for macOS to automatically start one.

[y-lee]

(On 7.2.4, I just added two existing Time Machine backups as targets to my Mac. After adding the first target, the first auto backup failed with the above error message. After rebooting the backup worked. I had to repeat this process with the second target. I looked all around with Disk Utility, hdiutil, and mount, but could not see anything I could remove/unmount to avoid rebooting.)