Modify readme to include cloning the repo
Modify readme to include cloning the repo

- As of the elasticsearch@5.6 change, we use the elasticsearch@5.6.rb
file within this repo. The previous readme instructions did not include
a step to clone the repo; rather, it downloaded only the shell script from
the repo. This means that the elasticsearch step would fail, since there
would be no local `elasticsearch@5.6.rb` file.

policygenius/laptop,policygenius/laptop