Create a best practice guide for managing Github

[apburnes]

To clarify for customers, create a best practice guide for customers to manage their Github orgs and repos.

Acceptance Criteria

• [x] Create a doc to share with customers
• [x] Pull information we currently provide customers
• [x] Show how to invite user and manage roles in Github Orgs
• [x] Show how to pull activity logs from Github org

Best Practices Doc