scripts/documentation-file-ref-check: fix help message

The name of the --fix option was renamed, but it was not
changed at the quick help message.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Jonathan Corbet <corbet@lwn.net>

scripts/documentation-file-ref-check

@@ -21,7 +21,7 @@ GetOptions(
 );
 
 if ($help != 0) {
-    print "$scriptname [--help] [--fix-rst]\n";
+    print "$scriptname [--help] [--fix]\n";
     exit -1;
 }