Update README to reflect v4/v3 branches
Update README to reflect v4/v3 branches

opensciencegrid/htcondor-ce,brianhlin/htcondor-ce,brianhlin/htcondor-ce,brianhlin/htcondor-ce,matyasselmeci/htcondor-ce,opensciencegrid/htcondor-ce,matyasselmeci/htcondor-ce,matyasselmeci/htcondor-ce,opensciencegrid/htcondor-ce