fixed cell for topfarm installation

docs/notebooks/MongoDB_recorder.ipynb

docs/notebooks/bathymetry.ipynb

docs/notebooks/cost_models.ipynb

docs/notebooks/design_variables.ipynb

docs/notebooks/drivers.ipynb

docs/notebooks/hub_height_optimization.ipynb

docs/notebooks/layout_and_loads.ipynb

docs/notebooks/problems.ipynb

docs/notebooks/regular_grid_optimization.ipynb

docs/notebooks/roads_and_cables.ipynb

docs/notebooks/unconstrained_wake_steering.ipynb

docs/notebooks/wake_steering_and_loads.ipynb