radio: added quotes for smart callback name in the documentation.
radio: added quotes for smart callback name in the documentation.

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