Add Apache Kafka as an input resource

Author: spelluru

articles/stream-analytics/stream-analytics-define-inputs.md

@@ -16,7 +16,8 @@ Stream Analytics has first-class integration with Azure data streams as inputs f
 - [Azure Event Hubs](https://azure.microsoft.com/services/event-hubs/)
 - [Azure IoT Hub](https://azure.microsoft.com/services/iot-hub/) 
 - [Azure Blob storage](https://azure.microsoft.com/services/storage/blobs/) 
-- [Azure Data Lake Storage Gen2](../storage/blobs/data-lake-storage-introduction.md) 
+- [Azure Data Lake Storage Gen2](../storage/blobs/data-lake-storage-introduction.md)
+- [Apache Kafka](stream-analytics-define-kafka-input.md)
 
 These input resources can live in the same Azure subscription as your Stream Analytics job or a different subscription.