change -c description

lxc-backup.sh

@@ -52,7 +52,7 @@ Options:
   -d  Directory where backups will be stored (default: current directory)
   -t  Manager type: lxc or incus (default: lxc)
   -x  Compression algorithm (e.g. gzip, zstd, none)
-  -c  Cleanup old backups keeping a set number (default: 2)
+  -c  Cleanup old backups and keep last <n> (default: keep all)
   -h  Show this message
 EOF
   exit 1