Fixing alt text

Author: v-dirichards

articles/hdinsight/hdinsight-overview.md

@@ -64,7 +64,7 @@ You can use HDInsight to perform interactive queries at petabyte scales over str
 
 You can use HDInsight to process streaming data that's received in real time from different kinds of devices. For more information, [read this blog post from Azure that announces the public preview of Apache Kafka on HDInsight with Azure Managed disks](https://azure.microsoft.com/blog/announcing-public-preview-of-apache-kafka-on-hdinsight-with-azure-managed-disks/).
 
-:::image type="content" source="./hadoop/media/apache-hadoop-introduction/hdinsight-architecture-iot-new.png" alt-text="HDInsight architecture: Internet of Things":::
+:::image type="content" source="./hadoop/media/apache-hadoop-introduction/hdinsight-architecture-iot-new.png" alt-text="Screenshot of the HDInsight architecture: Internet of Things.":::
 
 ### Hybrid