Changes for the che-docs repository

We need the following changes on the che-docs repository:

1. Migrate the https://github.com/eclipse/che-docs/ repository to the https://github.com/eclipse-che organization (keeping same access rights).
2. Switch the default branch from master to main.
3. Branch protection rule for main and master:
   • Require status checks to pass before merging: Build and validate pull request(rather than link-checker).
   • Require branches to be up to date before merging: false.