feat+docs: add complete setup docs/guides

[oleonardolima]

Describe the enhancement

A step towards the adoption of Oblivious HTTP, in my view, is making it simple for any end-user set up and host their own ohttp-relay, even as an ephemeral one for timed use (?).

I don't know any other FOSS Oblivious HTTP relay projects, besides this one. AFAIK you can use hosted "alike" versions with Cloudflare Workers and Fastly OHTTP Relay.

ohttp-relay is pretty self-contained and somewhat simple to run and host, but I think we could cover some ground and have richer/complete docs for any user-level.

I have some issues in mind that could help towards the goal afore mentioned:

• [ ] docs: add initial setup docs with standard nginx & nohup usage on common cloud infrastructure
• [ ] feat+docs(docker): add standard minimal Dockerfile without Nix dependency, and usage documentation
• [ ] feat+docs(nix): add Nix Module usage and deployment documentation
• [ ] feat(installer): add a friendly setup script guiding user through ohttp-relay setup on common VM systems (?)

I got these inspirations on how we do at fedimint, having the docker images, and the setup script that relies on them allows any user-level to pretty much setup a federation in instants. While having nixpkgs and modules for sophisticated users.

Use case

Improve adoption, and usage of ohttp-relay by making it simple and easy to host. **Additional context** TBD

[oleonardolima]

I would also add a future-research topic on relying specifically in nginx, does other industry-level proxy/webserver can handle TLS termination as we need?

AFAIK know Caddy doesn't, but maybe traeffik?