Remove "Puppet Environments" and instead add a use case overview for environments

[dnsmichi]

trafficstars

• Puppet environments (test, stage, production)
• Deployment environments from CI system
• etc

[dnsmichi]

Also, not everyone in the training lknows what Puppet is.

[theFeu]

The "Puppet Environments" should probably be removed and the beginning of the CI/CD should be revamped for a more beginner friendly alternative.

[martialblog]

I vote we remove the Puppet Env section