AS UI redirect for experimental to stable Gradle migration guide

- This guide may be moved over to DAC when AS 2.2 goes stable.

Change-Id: Ia29bb75832f01efc8175db45f8fd08d5013d715e
diff --git a/docs/html/_redirects.yaml b/docs/html/_redirects.yaml
index f287f51..ae858fe 100644
--- a/docs/html/_redirects.yaml
+++ b/docs/html/_redirects.yaml
@@ -843,6 +843,8 @@
   to: http://tools.android.com/tech-docs/test-recorder
 - from: /r/studio-ui/export-licenses.html
   to: http://tools.android.com/tech-docs/new-build-system/license
+- from: /r/studio-ui/experimental-to-stable-gradle.html
+  to: http://tools.android.com/tech-docs/new-build-system/gradle-experimental/experimental-to-stable-gradle
 - from: /reference/org/apache/http/...
   to: /about/versions/marshmallow/android-6.0-changes.html#behavior-apache-http-client
 - from: /shareables/...