docs: add links from widget classes to tutorials

Change-Id: I817e885524951853182b0458df4a32dea1614243
diff --git a/core/java/android/widget/ToggleButton.java b/core/java/android/widget/ToggleButton.java
index dc791e3..3b680e8 100644
--- a/core/java/android/widget/ToggleButton.java
+++ b/core/java/android/widget/ToggleButton.java
@@ -26,6 +26,9 @@
 /**
  * Displays checked/unchecked states as a button
  * with a "light" indicator and by default accompanied with the text "ON" or "OFF".
+ *
+ * <p>See the <a href="{@docRoot}resources/tutorials/views/hello-formstuff.html">Form Stuff
+ * tutorial</a>.</p>
  * 
  * @attr ref android.R.styleable#ToggleButton_textOn
  * @attr ref android.R.styleable#ToggleButton_textOff