Update WebDriver.php

[ThomasLandauer]

Reorganizing the docs about setup. First step of what I suggested at #30 (comment)

Once you've merged all my 3 PR's from today, please rebuild the page https://codeception.com/docs/modules/WebDriver, so I can see what this looks like so far.

Questions:

• "Note that Selenium 3.8 renamed this capability from chromeOptions to goog:chromeOptions" This obviously only applies when using Selenium - i.e. when using ChromeDriver directly, it's still chromeOptions?
• Depending on what you answer at Docs: Drop Selenium and PhantomJS? #28 (comment), I would suggest: Tell people to start without Selenium, and see how far they'll get. Reason: Selenium installation is cumbersome, and might not be necessary. So I'd like to "sell" Selenium as (a) tool for troubleshooting if they run into problems, and (b) power tool giving additional options (which?).

Next step (depending on how much time I have :-)
I'd like to shorten https://codeception.com/docs/03-AcceptanceTests#WebDriver:

• Remove everything that's already present here (e.g. installation instructions)
• The "Acceptance Tests" page should be an overview page for new users, showcasing Codeception's cool features. Configuration details (like e.g. the lengthy SmartWait examples) don't belong there, and should be moved to the WebDriver module page.