Remove MoinMoin stuff from search results on wiki

[Jason Merrill]

A quick suggestion about the homepage/wiki: it would be helpful to remove pages
that are about MoinMoin from the wiki search results if possible.  For instance,
the first search result for 'install' points to information about installing
MoinMoin, whereas I'm sure most users would be looking for information on how to
install Bazaar.

Cheers,

Jason Merrill