Add unit testing/tsqlt-docker section

Author: segovoni

samples/containers/README.md

@@ -1,3 +1,7 @@
 __[replication](replication/)__
 
-Example of SQL Server Replication in containers. This demo uses docker-compose to start two SQL Server containers; one that acts as the publisher and distributor, and the other as the subscriber in a push snapshot configuration. 
+Example of SQL Server Replication in containers. This demo uses docker-compose to start two SQL Server containers; one that acts as the publisher and distributor, and the other as the subscriber in a push snapshot configuration. 
+
+__[unit testing/tsqlt-docker](unit-testing/tsqlt-docker/)__
+
+Example describes how to automate the testing for one or more SQL Server objects using tSQLt, Docker, and GitHub Actions.