Move static content to GitHub pages

[manics]

https://docs.github.com/en/free-pro-team@latest/github/working-with-github-pages/about-github-pages

1. Since this will be a top level site https://www.openmicroscopy.org/ it has to be in a repo called <USER-OR-ORG>.github.io, so either ome/ome.github.io or use new GitHub user e.g. ome-www/ome-www.github.io.
2. Add a CNAME file to this repo containing www.openmicroscopy.org
3. Add a DNS CNAME www.openmicroscopy.org ➔ <USER-OR-ORG>.github.io
4. Edit the baseurl in _config.yml

[sbesson]

Adding a few thoughts, potentially to be captured as separate issues:

• why is the new repo a requirement? we have ome/ome-help and ome/omero-figure successfully deploying to help.openmicroscopy.org and figure.openmicroscopy.org
• in addition to the static website, the content the playbooks under https://github.com/ome/prod-playbooks/tree/master/www will need to be reviewed and at least the critical parts added to the config
• from a quick glance, the most important bit missing are the XSD schemas hosted under www.openmicroscopy.org/Schemas previously proxied from another server. Some in-progress work and thoughts are captured in Migrate generated schemas pages under static website #286 (comment) but this requires some more input
• from previous experience with help/figure, one downside of deploying with GitHub pages using a custom CNAME is that it complicates the staging of an integration branch. Alternatively would there be a mechanism to stage per-PR builds?

[manics]

1. I was going by what's implied by the docs, but if you've got a working configuration that's great!
2. I think the tradeoff between easier production deployment and resilience is worth the additional configuration required on the CI side. One workaround is to have a permanently open PR that changes the configuration of the built CI site.