AppServices: We need to specify the API endpoints under Querying #1325
Description
https://matrix.org/docs/spec/application_service/unstable.html#querying
The application service API includes two querying APIs: for room aliases and for user IDs.
We never mention what these should be, nor the expected request/response, leaving people to reverse-engineer current implementations.
We do mention it in the HTTP APIs section. We should combine these two sections into just "Querying".