updated spec slightly

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402990

dlib/image_keypoint/surf_abstract.h

@@ -66,6 +66,7 @@ namespace dlib
     {
         /*!
             WHAT THIS OBJECT REPRESENTS
+                This object represents a detected SURF point.
         !*/
 
         interest_point p;