Copyediting of the documentation. Attempting to fix various awkward

phrasings, grammar, and spelling. Consistently capitalize "pgBadger"
as such, except for command examples which should stay all-lowercase.

Note also, there is a link in CONTRIBUTING to http://dalibo.github.com/pgbadger/documentation.html which seems to be broken at the moment, I wasn't sure where the current version of that page existed.