mat2: standardize the help messages format

This is a cosmetic patch only.

Signed-off-by: Antoine Tenart <antoine.tenart@ack.tf>

README.md

@@ -80,7 +80,7 @@ optional arguments:
                         (policy should be one of: abort, omit, keep) [Default:
                         abort]
   --inplace             clean in place, without backup
-  --no-sandbox          Disable bubblewrap's sandboxing.
+  --no-sandbox          Disable bubblewrap's sandboxing
   -v, --version         show program's version number and exit
   -l, --list            list all supported fileformats
   --check-dependencies  check if mat2 has all the dependencies it needs

mat2

@@ -57,7 +57,7 @@ def create_arg_parser() -> argparse.ArgumentParser:
     parser.add_argument('--inplace', action='store_true',
                         help='clean in place, without backup')
     parser.add_argument('--no-sandbox', dest='sandbox', action='store_true',
-                        default=False, help='Disable bubblewrap\'s sandboxing.')
+                        default=False, help='Disable bubblewrap\'s sandboxing')
 
     excl_group = parser.add_mutually_exclusive_group()
     excl_group.add_argument('files', nargs='*', help='the files to process',