text: Title: Update documentation with custom binary path information
  Body: ie: Update https://splinter.readthedocs.io/en/latest/drivers/chrome.html with
  
  ```
  from selenium import webdriver
  
  chrome_options = webdriver.chrome.options.Options()
  chrome_options.binary_location = "/path/to/canary"
  browser = Browser('chrome', options=chrome_options)
  ```
  
  but for Firefox as well.