As ^ban^ says, the Help namespace is not searched by default. If you want your search to include Help pages as well, you need to either change your preferences as I described above, or use the Search button instead of the Go button, then tick the box named "Help" to enable searching for Help pages as well. Not that ticking the box on the Search page is not "sticky". It resets every time to you go back to that page. If you want it to stick, you need to change your wiki preferences.
Is there any way to have the help pages searched by default for everyone?
