ASACORE-981 About Feature - fixed documentation errors

Fixed some minor spelling error.  Some comments referenced
RegisterAboutListener when they should have been referencing
WhoImplements.

Add some additional documentation to add clarity.

Change-Id: I4afc46fed4ce4f288edeba2fcbe7d3bb8ee4a5ef
Signed-off-by: George Nash <georgen@qce.qualcomm.com>