Updating example in On Input Understanding within note (#2984)

Updating in response to discussion on #2982

Author: Andrew Kirkpatrick

understanding/20/on-input.html

@@ -37,7 +37,7 @@ <h2>Intent of On Input</h2>
       <div class="note">
 
          <p>This Success Criterion covers changes in context due to changing the setting of a
-            control. Clicking on links or tabs in a tab control is activating the control, not
+            control. Clicking on links or buttons is activating a control, not
             changing the setting of that control.
          </p>