better explanation for querying collections

[timaschew]

• On https://docpad.org/docs/template-data#querying
  you don't see the findAllLive function of the database object - which is a common use case (in many skeletons projects you see this)
• The link to Query-Engine should go directly to the documentation: http://bevry.me/learn/queryengine-guide
• Add an hint/example, that you can query alll the meta data and special attributes (http://docpad.org/docs/meta-data) like relativeOutDirPath
• The query values seems to be strings, but thats wrong, they are regex - this should be mentioned due to avoiding problems like this: http://stackoverflow.com/questions/18375086/how-to-get-collections-from-sub-folder-in-docpad/18482027#18482027 or this http://stackoverflow.com/questions/15494422/collection-to-be-generated-from-all-the-sub-folders-into-one

[greduan]

@timaschew Thanks for finding these errors. Could you make a pull request for this one because I have a really limited amount of internet time per day now. Thanks. 😄