Update CNAME

You can normally only configure either a custom subdomain or a custom apex domain for a GitHub Pages site, but there is one notable exception: the www subdomain. If you configure both an apex domain (e.g. example.com) and a matching www subdomain (e.g. www.example.com) following the instructions below, GitHub's servers will automatically create redirects between the two. Specifically, www.example.com will redirect to example.com if your CNAME file contains example.com, and example.com will redirect to www.example.com if your CNAME file contains www.example.com. https://help.github.com/articles/setting-up-a-custom-domain-with-github-pages#subdomains