@conorgil145 (Couldn't reply; too nested)
We existed (much) after Swagger. I've never used Swagger myself, although I briefly played around with the client. Not really that inspired by them.
We use APIDoc (and eventually want to add more) as our "schema", and you can auto-sync from GitHub. Or, you can add it manually.
I am familiar with RTD (moreso the .org version than the .com); they're great. However, they mostly just host Sphinx/markdown/etc files. ReadMe does much more (support section, API explorer, "Suggest Edits", show user keys in the code, etc). If you want to write docs locally and deploy, use RTD. If you want something more full-featured, check out ReadMe.