API signature is not shown for complex signatures

[gheoan]

I'm submitting a bug report

• Browser:
  Chrome 62 | Firefox 57

Current behavior:
In the API docs on http://aurelia.io complex signatures are not displayed.

Expected/desired behavior:

• What is the expected behavior?
  For example on http://aurelia.io/docs/api/fetch-client/interface/Interceptor/property/request the return signature should be Request | Response | Promise<Request | Response> and on http://aurelia.io/docs/api/router/interface/RoutableComponentActivate/method/activate it should be Promise<void> | PromiseLike<void> | IObservable | void.

• What is the motivation / use case for changing the behavior?
  Accurate type definitions.