docs(tutorial): Log target values and not the events

We want to log the input values and not the keypress events.

doc/tutorial/basics.md

@@ -52,27 +52,33 @@ var input = Rx.Observable.fromEvent(document.querySelector('input'), 'keypress')
 
 // Filter out target values less than 3 characters long
 input.filter(event => event.target.value.length > 2)
+  .map(event => event.target.value)
   .subscribe(value => console.log(value)); // "hel"
 
 // Delay the events
 input.delay(200)
+  .map(event => event.target.value)
   .subscribe(value => console.log(value)); // "h" -200ms-> "e" -200ms-> "l" ...
 
 // Only let through an event every 200 ms
 input.throttleTime(200)
+  .map(event => event.target.value)
   .subscribe(value => console.log(value)); // "h" -200ms-> "w"
 
 // Let through latest event after 200 ms
 input.debounceTime(200)
+  .map(event => event.target.value)
   .subscribe(value => console.log(value)); // "o" -200ms-> "d"
 
 // Stop the stream of events after 3 events
 input.take(3)
+  .map(event => event.target.value)
   .subscribe(value => console.log(value)); // "hel"
 
 // Passes through events until other observable triggers an event
 var stopStream = Rx.Observable.fromEvent(document.querySelector('button'), 'click');
 input.takeUntil(stopStream)
+  .map(event => event.target.value)
   .subscribe(value => console.log(value)); // "hello" (click)
 ```