Added "closed" in H2

Author: garyericson

articles/sql-database/sql-database-machine-learning-services-overview.md

@@ -44,7 +44,7 @@ In addition to the pre-installed packages, you can [install additional packages]
 
 <a name="signup"></a>
 
-## Sign up for the preview
+## Sign up for the preview (closed)
 
 > [!IMPORTANT]
 > Sign up for Azure SQL Database Machine Learning Services (preview) is currently **closed**.