added title; minor typo fixes
added title; fixed link to configuration
refactored sidebar sections to group related topics together under a section that encompasses what they are about, and communicates to a user that this is the go-to section for provisioning/deploying etc. a druid cluster
Refactored modules section for better flow/readability and added link to extending druid
added title
adjusted size of first section head to match others
Merge branch 'master' into igalDruid
Merge pull request #320 from metamx/igalDruid

Igal druid