Add option markup in osc doc

KATO Tomoyuki · KATO Tomoyuki · commit 084e4fbf1b5e · 2016-09-25T14:15:27.000+09:00
To avoid unintended hyphen concatenation: "openstack –help"

Change-Id: I6e8a1c453c5964bea4adc47d167904ab8ce8abda
diff --git a/doc/source/man/openstack.rst b/doc/source/man/openstack.rst
@@ -12,7 +12,7 @@ SYNOPSIS
 
 :program:`openstack help` <command>
 
-:program:`openstack` --help
+:program:`openstack` :option:`--help`
 
 
 DESCRIPTION
