Update 1.md

Updated the prerequisites.

labs/docker-101/1.md

@@ -18,6 +18,12 @@ This is a hands-on Lab, but each example builds on the previous and explains why
 
 Thanks to the Cisco Live EU 2017 workshop "Introduction to Containers" for portions of this Learning Lab. Further reading is available in the excellent docker introduction at [imapex.io](https://github.com/imapex-training/mod_adv_docker/blob/master/README.md).
 
+## Prerequisite
+
+ * Install Docker on your system.
+ * Create your Docker ID.
+  For more information about creating the Docker ID, see [Docker docs](https://docs.docker.com/docker-id/).
+
 ## Installing Docker
 The Docker engine runs and manages containers on a host machine. The Docker client tools control the Docker engine. Both the Docker engine and the Docker client tools are now distributed by default as part of many Linux distributions. The engine and client tools are also available for download directly from [Docker.com](http://www.docker.com).