Oddly enough, I don't see any mention of this in the github article explaining how to set up a custom domain: https://help.github.com/articles/setting-up-a-custom-domain-...
echo example.com > CNAME
Then point it (if apex) at 207.97.227.245.
echo example.com > CNAME
Then point it (if apex) at 207.97.227.245.