Unify OpenAPI spec and API documentation

[nbbaier]

While working on #101, I noticed that there are discrepancies between the OpenAPI specification and the API documentation. The table below summarizes the differences. (See also #100)

Endpoint	OpenAPI	Docs website	Notes
GET /v1/me	✓	✓
GET /v1/me/likes	✓	✓
GET /v1/me/runs		✓
GET/v1/me/comments	✓	✓
GET /v1/me/references	✓		resolved by #101
POST /v1/vals	✓	✓
PUT /v1/vals	✓		resolved by #101
GET /v1/vals/{val_id}	✓	✓
PUT /v1/vals/{val_id}	✓
DELETE /v1/vals/{val_id}	✓	✓
GET /v1/vals/{val_id}/versions	✓	✓
POST /v1/vals/{val_id}/versions	✓	✓
GET /v1/vals/{val_id}/versions/{version}	✓	✓
DELETE /v1/vals/{val_id}/versions/{version}	✓	✓
GET /v1/vals/{val_id}/runs		✓
GET /v1/users/{user_id}		✓
GET /v1/users/{user_id}/vals	✓	✓
GET /v1/alias/{username}	✓	✓
GET /v1/alias/{username}/{val_name}	✓	✓
GET /v1/search/vals	✓
GET /v1/eval/{expression}	✓	✓
POST /v1/eval	✓	✓
GET /v1/run/{username}.{val_name}	✓	✓
POST /v1/run/{username}.{val_name}	✓	✓
GET /	✓	✓
POST /	✓	✓

[Xkonti]

That's some useful table @nbbaier. I'll take a look at fixing those discrepancies shortly.