[Yum] a few more repoquery docs

[seth vidal]

After answering a question on repoquery this morning I realized I should
have typed something up long ago:

 http://yum.baseurl.org/wiki/RepoQuery

edits/comments/questions welcome.

Also if you have docs you'd like to contribute to the yum guides:
http://yum.baseurl.org/wiki/Guides

please chime in - wiki access can be given quickly and easily for people
with docs in hands.

Your docs don't have to be complete and authoritative they can be a good
start on something.

-sv