Fix copypasta in documentation

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/test_psa_constant_names.py b/tests/scripts/test_psa_constant_names.py
index b3fdb8d..15b83d8 100755
--- a/tests/scripts/test_psa_constant_names.py
+++ b/tests/scripts/test_psa_constant_names.py
@@ -365,7 +365,7 @@
                         help='Program to test')
     parser.add_argument('--show',
                         action='store_true',
-                        help='Keep the intermediate C file')
+                        help='Show tested values on stdout')
     parser.add_argument('--no-show',
                         action='store_false', dest='show',
                         help='Don\'t show tested values (default)')