Fix a small typo in `stdin` example
Fix a small typo in `stdin` example

s/--stdin-filenam/--stdin-filename/
jayme-github/restic,middelink/restic,restic/restic,arithmetric/restic,middelink/restic,stuertz/restic,ar-jan/restic,fawick/restic,ckemper67/restic,fawick/restic,byo/restic,kurin/restic,ar-jan/restic,restic/restic,kurin/restic,jayme-github/restic,stuertz/restic,byo/restic