update readme

[lstanish]

@dawsonfairbanks Need to update the readme with instructions on branching instead of forking. Let me know if you need help!

[dawsonfairbanks]

Hi @lstanish. I created and merged a branch to the master repository but I am not able to push due to permission error. I think that if the permissions are set then only pull requests from a forked repository can be merged to the master repository. I might be wrong? I updated the README file with the instructions on how to branch from a master repository in my forked repository. https://github.com/dawsonfairbanks/SummitMicrobes

Not sure how much help this is given the permission limitations..