Need to add conda activate to the get started instructions

[mooreryan]

Something like:

Ensure that you have created then conda environment using the environment.yml file included in this repository.

# Create conda environment
conda env create -f environment.yml

# Register the kernel
python -m ipykernel install --user --name=nigms_sandbox_ud --display-name "Python (nigms_sandbox_ud)"

Then, when starting the notebook, select the "Python (nigms_sandbox_ud)" kernel from the list.