This option really helps people get a start for the ChangeLog, so it should be very visible. I considered adding text about --user and --email to the help text, but I suspect these are used so seldom that it wasn't worth the added clutter. In the rare case that one may feel the need to use them, then the error message from the tool will tell you about them.
Created attachment 32840 [details] Proposed fix.
Comment on attachment 32840 [details] Proposed fix. r=me
Committed as http://trac.webkit.org/changeset/45968