Update container-instances-volume-azure-files.md

Adding limitation

Author: tysonfms

articles/container-instances/container-instances-volume-azure-files.md

@@ -16,6 +16,7 @@ By default, Azure Container Instances are stateless. If the container is restart
 
 ## Limitations
 
+* Azure Storage doesn't support SMB mounting of file share using managed identity
 * You can only mount Azure Files shares to Linux containers. Review more about the differences in feature support  for Linux and Windows container groups in the [overview](container-instances-overview.md#linux-and-windows-containers).
 * Azure file share volume mount requires the Linux container run as *root* .
 * Azure File share volume mounts are limited to CIFS support.