Separate contribution workflow information into two parts #120

[HeikoKlare]

This is a proposal for addressing https://github.com/eclipse-platform/.github/issues/120#issuecomment-1517443447 and https://github.com/eclipse-platform/.github/issues/120#issuecomment-1517448655.

The CONTRIBUTING.md describes the contribution workflow combining the information for how to set up and manage a fork and for how to create and process a pull request.

This change separates the two parts of the contribution process into separate sections. In addition, is extends the explanation of how to manage the local clone for a fork by an alternative workflow of having the main Eclipse repository as the origin remote.

To conform to recent repository merges, the change also clean ups the list of repositories in the Eclipse platform organization.

Contributes to https://github.com/eclipse-platform/.github/issues/120

[merks]

It’s a good idea!

[HeikoKlare]

@BeckerWdf Since you liked the idea (https://github.com/eclipse-platform/.github/issues/120#issuecomment-1517448655) and updated the description before, it would be great to also have your feedback on this 🙂