(minor) added some documentation for SiteLinkEditTool + minor cleanup

* cleanup of templates used in SiteLinkEditTool
* SiteLinkEditTool.getEmptyStructure() will return more useful output than before
* minor documentation cleanups

Change-Id: I4f2e4405cf02f4dab9e21f0c8d10e553848b078b
Merge "(minor) added some documentation for SiteLinkEditTool + minor cleanup"