Support www subdomain for landing page

[johnmcollier]

GitHub recommends that for pages hosted under an Apex domain, like https://devfile.io, that the www subdomain also be configured.

https://docs.github.com/en/pages/configuring-a-custom-domain-for-your-github-pages-site/managing-a-custom-domain-for-your-github-pages-site#configuring-an-apex-domain-and-the-www-subdomain-variant provides some instructions on doing so, and it should be pretty straightforward for us to do.

• Add DNS entry for www subdomain to devfile.io