Add content describing how project team can receive (significant) code contributions

Submitted by Wayne Beaton `@wbeaton`

Starting point:

Contributors make some sort of public announcement that the content will be delivered to the project
If the source code is not already in a public repository, it will have to be delivered to an existing project committer in some way
The source needs to be handed off to the IP Team for their review as a "project code" contribution to an existing project
Any developers who are coming to the project along with the code need to be voted in as committers
When the IP Team gives the go-ahead, either the existing public repository needs to be moved to the Eclipse Foundation, or a new repository can be created and used as a home for the code. --