Rework WindowsWorkerSetup.md

[robertmaynard]

Once the ability to launch windows executables from Windows Subsystem for Linux has rolled out, we need to rewrite the guide to use that approach.

more info:
https://blogs.msdn.microsoft.com/wsl/2016/10/19/windows-and-ubuntu-interoperability/

[robertmaynard]

OpenSSH can now be used with windows so that is also an approach:

* Settings -> Apps -> Optional Features -> Add a feature -> OpenSSH Server
* services.msc -> OpenSSH Server -> Properties -> Startup Type -> Automatic (delayed), Start
* sshd_config is found at `C:\ProgramData\ssh\sshd_config`
* Create a `%USERPROFILE%\.ssh\authorized_keys` file with a public key.