elm elm_gengrid.h: Added more description to gengrid documentation.
elm elm_gengrid.h: Added more description to gengrid documentation.

SVN revision: 79501

tasn/elementary,FlorentRevest/Elementary,tasn/elementary,FlorentRevest/Elementary,FlorentRevest/Elementary,FlorentRevest/Elementary,rvandegrift/elementary,rvandegrift/elementary,tasn/elementary,tasn/elementary,rvandegrift/elementary,tasn/elementary,rvandegrift/elementary