Document how to use TestCafe in WSL

We should add the following content to our docs: https://github.com/DevExpress/testcafe/issues/1640#issuecomment-510491429

For the Chrome Linux option, there are several ways to enable GUI testing: https://medium.com/@dhanar.santika/installing-wsl-with-gui-using-vcxsrv-6f307e96fac0 https://devblogs.microsoft.com/commandline/whats-new-in-the-windows-subsystem-for-linux-september-2020/#gui-apps