Delete the 'master' branch and make 2-master to main branch
The OStree repository is confusing users because the master branch shows 'this is the Pulp3 plugin for OSTree....". This is really just a stub and the plugin is in no way functional.
Delete the 'master' branch and make the default branch '2-master'. This is similar to what was done to the pulp/pulp repository which is also a Pulp2 only repository.