README.md in imgix-3.3.1 vs README.md in imgix-3.4.0

@@ -228,9 +228,11 @@
 path.noise_reduction(50,50)
 ```
 
 ## Purge Cache
 
+**Deprecation Notice:** The API keys used in `Imgix::Client#purge` version `3.3.X` have been deprecated. To utilize the updated `Imgix::Client#purge` method in version `4.0.0`, please regenerate your API key at `http://dashboard.imgix.com/api-keys`. Feel free to reach out to our [support line]([e-mail]) if you have any questions or concerns.
+
 If you need to remove or update an image on imgix, you can purge it from our cache by initializing a client with your api_key, then calling Imgix::Client#purge with the resource path.
 
 ```ruby
 client = Imgix::Client.new(domain: 'your-subdomain.imgix.net', api_key: 'your-key')
 client.purge('/images/demo.png')