Try and help people who don't understand what optional means

Author: thespad

roles/generate-jenkins/templates/README_SNIPPETS/USAGE.j2

@@ -2,6 +2,8 @@
 
 To help you get started creating a container from this image you can either use docker-compose or the docker cli.
 
+**Unless a parameter is flaged as "optional", it is *mandatory* and a value must be provided.**
+
 ### docker-compose (recommended, [click here for more info]({{ lsio_docs_url }}/general/docker-compose))
 
 {% include "README_SNIPPETS/DOCKER_COMPOSE.j2" | trim %}