[feature] Complete Grassim documentation

Summary

Missing methods argument types in Grassim class docstrings

Current behavior

Missing methods argument types in Grassim class docstrings

Desired behavior

Add Missing methods argument types in Grassim class docstrings

Sources

Linked features or branches

Changes to be made in https://gitlab.uliege.be/deal-public/pase/-/tree/develop/MODULES/CROPS/GRASSIM?ref_type=heads