Writing an appspec.yml File for Deployment from GitHub to AWS CodeDeploy

I'd like to make it so that a commit to our GitHub repo automatically deploys code (using CodeDeploy) to our EC2 instances. I'm not clear what to use for the 'source' entry under the 'files' section in the appspec.yml file. I've found some examples for using a local git repo, but I was wondering if someone could help me out?

Thanks in advance for your help!