Update readme with architectures instruction

README.md

@@ -115,10 +115,15 @@ To add a new service (see the [backend v4](./services/backendv4/) for an extensi
 3. create the `docker-compose.yaml` file with the required dependencies (if any)
 4. eventually include any service in (3) which is specific to the service and not shared across the global setup
 5. eventually add the condition on the backend version (e.g. [here](./services/frontend/docker-compose.yaml#L14))
-6. eventually create a `config` folder if it requires configuration
-7. eventually add a `README.md` file in the service
-8. include the reference to (3) to the global [docker-compose include list](docker-compose.yaml#L2)
-9. eventually update the main [README.md](README.md)
+6. eventually add the platform field, as described [here](#supported-os-architectures)
+7. eventually create a `config` folder if it requires configuration
+8. eventually add a `README.md` file in the service
+9. include the reference to (3) to the global [docker-compose include list](docker-compose.yaml#L2)
+10. eventually update the main [README.md](README.md)
+
+## Supported OS architectures
+
+Since some images are not built with multi-arch, in particular the SciCat ones, make sure to specify the platform of the service in the docker-compose, when needed, to avoid possible issues when running `docker compose up` on different platforms, for example on MAC with arm64 architecture. See for example the [backendv4 docker-compose](./services/backendv4/docker-compose.yaml#L6)
 
 ## General use of SciCat