Add preview.openmm.org link to http://openmm.org/preview

[jchodera]

How is the http://docs.openmm.org redirect to http://openmm.org/documentation.html work, and who has control over that?

I've created a preview branch we should make changes to (or create PRs against). This will push the preview to http://openmm.org/preview/. We should create an http://preview.openmm.org redirect.

[jchodera]

@peastman : Do you know who has the keys to the domain name provider running openmm.org and the DNS records associated with it?

[peastman]

No idea about any of that.

[raimis]

This is no longer relevant. One can preview the modified website with GitHub Pages directly, .e.g https://raimis.github.io/openmm-org/.