Improve help text for organization's Drupal contributions field

People making organization pages aren't always greartly knowledgable about community contributions, while we really want to see them. psuway wrote, and megansanicki helped revise this

Self promote! These fields determine eligibility for the Drupal.org marketplace and show the Drupal community how much you've given back. Moderators use this information to respond to issues about community involvement, so it is important to list anything and everything relevant:

Still followed by the suggestions at http://drupal.org/node/1108710.