(docs) Port recent docs revisions to 1.6.x branch

This commit brings over the relevant changes from commit eb20757, since PuppetDB
1.6 will stay around a while for PE customers. I applied them by hand rather
than cherry-picking, to ensure no 2.1-isms would sneak over.
Merge pull request #1012 from nfagerlund/jul_2014_docs_16x

(docs) Port recent docs revisions to 1.6.x branch