Documentation to identify different Inner Source License Clauses

## Feature Request

### Description of Problem:
When I am looking for a guideline to create an inner source license I want a document that will identify different clauses that can be potentially included in my license. These clauses and options will be used in turn to create a license generator similar to Creative Commons

When I am working with the inner source licensing working group I would like to be able for people to add content to this document directly through pull requests such that there is tracking of contributions and a review process of additions.

### Potential Solutions:
- Create a clauses.md document in a new licenses doc folder on the inner source repository