rest backend: Improve documentation
rest backend: Improve documentation

middelink/restic,restic/restic,fawick/restic,mappu/restic,bchapuis/restic,ar-jan/restic,ckemper67/restic,ar-jan/restic,restic/restic,fawick/restic,jayme-github/restic,stuertz/restic,byo/restic,kurin/restic,middelink/restic,byo/restic,kurin/restic,jayme-github/restic,arithmetric/restic,stuertz/restic