Add initial build and run documentation
As the title says. After https://git.smhi.se/ec-earth/ecearth4/-/merge_requests/26 it makes sense to start documenting the building of ECE4 and making experiments.
As the title says. After https://git.smhi.se/ec-earth/ecearth4/-/merge_requests/26 it makes sense to start documenting the building of ECE4 and making experiments.