Updated Credits and References documents. Changed categoryItem to missionItem...

Updated Credits and References documents.  Changed categoryItem to missionItem in apollopaninit, apollopanstitcher, hicrop, hidtmgen and thmbasemap1 so that they appear in the proper location in the Table of Contents.  References Mantis #1331, #1332, and #951.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@4971 41f8697f-d340-4b68-9986-7bafba869bb8