Update install documentation

[mikekoss]

Note text below after git clone installs in:
~/software/KAI/KAI

it should be "git clone git@github.com:Keck-DataReductionPipelines/"

cd ~/software/KAI
git clone git@github.com:Keck-DataReductionPipelines/KAI.git
Install KAI by going to your cloned repository and running the setup.py script. For example:

conda activate iraf27
cd ~/software/KAI/
python setup.py install