The best CLI documentation generator I've found so far is Redoc[1].
There are tons of hosted solutions for docs (Apimatic, SwaggerHub, Stoplight, and Apicurio Studio).
My favorites are SwaggerHub[2] and Apicurio[3], because their editors are solid and they have good compatibility with all the nooks and crannies of the OpenAPI v3 spec.
1. https://github.com/Redocly/redoc
2. https://swagger.io/tools/swaggerhub
3. https://studio.apicur.io