add tuple and comment for prior to OTP 18

priv/templates/sup.erl

@@ -28,6 +28,8 @@ start_link() ->
 
 %% Child :: #{id => Id, start => {M, F, A}}
 %% Optional keys are restart, shutdown, type, modules.
+%% Before OTP 18 tuples must be used to specify a child. e.g.
+%% Child :: {Id,StartFunc,Restart,Shutdown,Type,Modules}
 init([]) ->
     {ok, { {one_for_all, 0, 1}, []} }.