Add deprecation notice

Author: matthewayne

README.md

@@ -1,4 +1,8 @@
-# The API.AI ruby gem
+# DEPRECATED The API.AI ruby gem
+
+| Deprecated |
+|-------|
+| This Dialogflow client library and Dialogflow API V1 [have been deprecated and will be shut down on October 23th, 2019](https://blog.dialogflow.com/post/migrate-to-dialogflow-api-v2/). Please migrate to Dialogflow API V2 and the [v2 client library](https://cloud.google.com/dialogflow-enterprise/docs/reference/libraries/ruby) |
 
 [![Gem Version](https://badge.fury.io/rb/api-ai-ruby.svg)](https://badge.fury.io/rb/api-ai-ruby)
 
@@ -207,4 +211,4 @@ See [LICENSE](LICENSE).
 ## Terms
 Your use of this sample is subject to, and by using or downloading the sample files you agree to comply with, the [Google APIs Terms of Service](https://developers.google.com/terms/).
 
-This is not an official Google product.
+This is not an official Google product.