manual: Add info on special items
manual: Add info on special items

Add info about handling of symlinks and bind-mounts.

Closes: #1014

restic/restic,middelink/restic,kurin/restic,fawick/restic,ar-jan/restic,ar-jan/restic,restic/restic,middelink/restic,fawick/restic,kurin/restic