Add documentation to cli to note user is responsible for chromedriver

[straker]

When the cli is installed it comes with chromedriver as a dependency. This works fine until Chrome releases 2 major version updates and then chromedriver doesn't work anymore. We need to add a note to the cli docs that note this problem, that the user is responsible for chromedriver versions, and how to set the chromedriver used in the CLI (it's currently the last item in the readme).

[not-my-profile]

I think this is also somewhat addressed by #680.