small fix on docs

Author: raulbrito

packages/ember-metal/lib/run_loop.js

@@ -306,7 +306,7 @@ Ember.run.once = function(target, method) {
     var sayHi = function() { console.log('hi'); }
     Ember.run.scheduleOnce('afterRender', myContext, sayHi);
     Ember.run.scheduleOnce('afterRender', myContext, sayHi);
-    // doFoo will only be executed once, in the afterRender queue of the RunLoop
+    // sayHi will only be executed once, in the afterRender queue of the RunLoop
   });
   ```