gh-pages; Draft registry content

[MikeRalphson]

A deployment of this code can be tested at https://spec.mermade.org.uk/registry/index.html

Before go-live, but not necessarily before merging this PR, probably requires a CONTRIBUTING.md or DEVELOPMENT.md with some guidelines.

[webron]

Approved with a vote by the @OAI/tsc.

[earth2marsh]

Thanks for the work, @MikeRalphson, and I approve of the general direction. Would you mind adding for history why the registry is being introduced (maybe link to an issue?) and what the TODOs are (like contributing.md and development.md) for this to be completed?

Also, could you remind me why the registry is part of this repo and not standalone? What are the arguments for/against?

[darrelmiller]

@earth2marsh We don't have a separate repo because we kept going back and forth on it and we decided not to create a separate repo for anything until it was obvious that it was needed.

[MikeRalphson]

@earth2marsh sorry it's taken me so long to come back to this.

History: the registry site is designed to be an extensible home for multiple registries, to satisfy the requests in issues such as (but not limited to) #845 and #1351

Todo Items:

• CONTRIBUTING.md - a guide to the process of registry entry addition and deprecation. This should probably live on the gh-pages branch, but with a pointer from the README on master - but I can see visibility reasons why this might not be preferred.
• GitHub issue and pull request templates to capture necessary information, ensure correct branch (gh-pages) used etc

While the site is in draft state, I believe we can treat it as a work-in-progress and aim to improve it iteratively. I would like to see PRs by @OAI/tsc members adding new registry entries, and maybe deprecating an existing entry, as a demo of the process.