orchestration: Add documentation for resource schema API call

We are missing documentation for /resource_types/{type_name}
which returns the interface schema for the specified resource
type.

Change-Id: If06c0a43ed29be3dfb78616b3f548870c278e5cb
orchestration: Add documentation for resource template API call

We are missing documentation for /resource_types/{type_name}/template
which returns a template representation of the specified resource type.

Change-Id: I54a94bb4b2770fa79dcf04f76a689644652bd186
Merge "orchestration: Add documentation for resource schema API call"
Merge "orchestration: Add documentation for resource template API call"