docs: raketasks: Add documentation on uploading to mounted shares
Fog has a local storage provider, which can be use to copy backups to locally mounted cifs / nfs / smb shares. This MR adds documentation to doc/raketasks/backup_restore.md in response to #3387.
@stanhu I found some time tonight and was able to get this started earlier than I initially expected, glad I could contribute.
See merge request !2246
