Refer to poligrain docs

The development workflow is the same as in poligrain. Hence, for now, please refer to the docs there

• Contributing (note that you have to adjust the URLs to point to this repo instead of the repo of poligrain)

• Tools for automation

Once the docs are not that much WIP, we can duplicated the doc pages for the development workflow, but for now it does not makes sense to have them two times and adjust them two times.