Add report photo upload

docs/API_SPEC.md

@@ -28,10 +28,10 @@ Authorization: Bearer <token>
 - `GET /reports/{id}/messages`: list report messages.
 - `POST /reports/{id}/assignments`: assign a team.
 - `POST /reports/{id}/feedback`: add citizen feedback.
+- `POST /reports/{id}/photos`: upload one or more multipart files for a report.
 
 ## Admin Reference Data
 - `GET|POST /admin/categories`
 - `GET|POST /admin/areas`
 - `GET|POST /admin/teams`
 - `GET /admin/stats/overview`
-