fix api naming

README.md

@@ -116,7 +116,7 @@ void setup() {
   uClock.setPPQN(uClock.PPQN_96);
 
   // you need to use at least one!
-  uClock.setOnPPQN(onPPQNCallback);
+  uClock.setOnOutputPPQN(onPPQNCallback);
   uClock.setOnStep(onStepCallback);
   uClock.setOnSync24(onSync24Callback);
 
@@ -399,7 +399,7 @@ void setup()
   uClock.init();
 
   // Set the callback function for the clock output to send MIDI Sync message.
-  uClock.setOnPPQN(onPPQNCallback);
+  uClock.setOnOutputPPQN(onPPQNCallback);
 
   // Set the callback function for the step sequencer on 16ppqn
   uClock.setOnStep(onStepCallback);