Should document the error - Please, set "CHROME_BIN"?

[felquis]

No binary for Chrome browser on your platform.
  Please, set "CHROME_BIN" env variable.

I'm on Linux Mint, with only Firefox installed.

[felquis]

Just installed Chrome and it worked well.

[mjackson]

I assume you're trying to run the tests? If so, glad you figured it out. But it's not something that we need to document for users of the library.