Remove the on_space from key01 in the docs

While in this part of the docs we do want to keep the bell (see key02), it
was an error in the code that it included this event in key01. Removing it
from here because adding this bit of code for key02 is a key (no pun) part
of the docs.

docs/examples/guide/input/key01.py

@@ -12,9 +12,6 @@ class InputApp(App):
     def on_key(self, event: events.Key) -> None:
         self.query_one(TextLog).write(event)
 
-    def key_space(self) -> None:
-        self.bell()
-
 
 if __name__ == "__main__":
     app = InputApp()