Add Kinesis event stream to pending changelog
Adds Kinesis's EventStream support to pending changelog,
### SDK Features
+* `service/kinesis`: Enable support for SubscribeToStream API operation ([#2402](https://github.com/aws/aws-sdk-go/pull/2402))
+ * Adds support for Kinesis's SubscribeToStream API operation. The API operation response type, `SubscribeToStreamOutput` member, EventStream has a method `Events` which returns a channel to read Kinesis record events from.
### SDK Enhancements
