docs: Add developer guide cross-references, Project ACRE, round 4

Change-Id: I1b43414aaec8ea217b39a0d780c80a25409d0991
diff --git a/test-runner/src/android/test/mock/MockContentResolver.java b/test-runner/src/android/test/mock/MockContentResolver.java
index 26eb8e4..6c91f4e 100644
--- a/test-runner/src/android/test/mock/MockContentResolver.java
+++ b/test-runner/src/android/test/mock/MockContentResolver.java
@@ -43,6 +43,12 @@
  *      Users can also set an authority's entry in the map to null, so that a provider is completely
  *      mocked out.
  * </p>
+ *
+ * <div class="special reference">
+ * <h3>Developer Guides</h3>
+ * <p>For more information about application testing, read the
+ * <a href="{@docRoot}guide/topics/testing/index.html">Testing</a> developer guide.</p>
+ * </div>
  */
 
 public class MockContentResolver extends ContentResolver {