Make start fails

[SvenMarcus]

After cloning and running make build I tried to run make start, but got the following error

ERROR: build path /root/kitodo_production_ocrd/_modules/kitodo-production-docker/docker-image either does not exist, is not accessible, or is not a valid URL.
make: *** [Makefile:38: start] Error 1

I believe this happens, because the submodules are not getting pulled during the build step.

[markusweigelt]

Now the initialization of the submodules is defined in the documentation as under prerequisites.