Fix three review findings in help text, example config and terms

The snapshot restore help splits its 40-word permissions sentence in
two. The snapshot-ID case leaves the parenthesis, and the temporary
space requirement gets its own sentence.

configs/config.example.yml gains a commented-out env entry, after
hostname, so its first line, which says the file shows every option,
is true again.

docs/REPOSTRUCTURE.md defines remote key in Terms, before the
marker-file section uses it.

Model: fable-5-1

internal/cli/snapshot_restore.go

@@ -48,10 +48,10 @@ typing it, so that it does not land in your shell history:
 
   export VAULTIK_AGE_SECRET_KEY="$(cat vaultik_backup_private_key.txt)"
 
-Also needs permission to read the backup destination store (and to list
+Also needs permission to read the backup destination store, and to list
 it when given a remote key, or a snapshot ID that is not in the local
-index), and free space in the temporary directory for the decrypted
-blobs.
+index. It also needs free space in the temporary directory for the
+decrypted blobs.
 
 Examples:
   # Restore entire snapshot