Add codelab redirect page.

Bug: 28767461
Change-Id: I0dd40da47df192c4734dfaffd343fff464dabbd1

Author: samtstern

codelabs/chat/README.md

@@ -0,0 +1,11 @@
+# Coming Soon - Codelab
+
+FirebaseUI 1.0.0 contains many API changes that make the original **Building a
+chat application with FirebaseUI for Android** codelab out of date. We are
+working hard to bring you a shiny new codelab as soon as we can.
+
+If you are using an older version of FirebaseUI and want to access the old
+codelab, [click here](https://github.com/firebase/FirebaseUI-Android/blob/a8d7988e0a9ec93650c864997124205816ea4856/codelabs/chat/README.md).
+
+If you want to learn how to build a fully featured Android app using all of
+the new Firebase APIs, [click here](https://codelabs.developers.google.com/codelabs/firebase-android).