Make API Docs out of Redocusaurus

[Zhao-Andy]

This adds the API docs based on our previous api_v0.yml file according to how Redoc would. This is generated through the Redocusaurus plugin: https://github.com/rohit-gohri/redocusaurus

Also adds some minor niceties like ignoring .env file, allowing development to run without ENV variables, and updating the URL.

[rhymes]

@Zhao-Andy does this mean that we'll have to copy over to this repository the api spec file everytime is changed or that we'll remove it from the main repo?

[Zhao-Andy]

@rhymes I think we can remove the entire docs/ folder from the forem/forem repo, including the api spec file!

I was in the middle of copying over the last few commits in the docs/ directory, and should have everything ported today. Will let the rest of the team know too.

[rhymes]

Thank you!