Environment management documentation

[audi5]

This issue is to request for documentation on the concepts of environments in Helix.

As an AEM user / customer, we have the concept of lower level / non production environments. However, with helix we understand that one could have an environment through branching. Each branch has it's own environment and the concept of lower environment testing is achieved by having a stage branch. A preview link from word would be generated which can be used for Content QA and then published. 

This topic needs some extensive documentation for new Helix users / developers to understand.

Requirements:
Explain the concept of environments in Helix
Explain the code gymnastics one could leverage from github in Helix
Explain how environments can be spun up, taken down when done.
Traffic routing / management.
Explain what role sharepoint plays in all this and the details around it.