Add Windows-specific instructions for ~/.ssh/config

[NicolasRouquette]

Add Windows-specific configuration details.

Currently, the instructions suggest:

Host hub.openveda.cloud
    User jovyan
    ProxyCommand websocat --binary -H='Authorization: token <YOUR-JUPYTERHUB-TOKEN>' asyncstdio: wss://%h/user/<YOUR-JUPYTERHUB-USERNAME>/sshd/

On Windows, it may be necessary to install a Windows-specific build of websocat.

Then, instead of asyncstdio:, we have to use - instead, so the configuration becomes:

Host hub.openveda.org
  User jovyan
  ProxyCommand C:/<WEBSOCAT INSTALL FOLDER>/websocat.exe --binary -H="Authorization: token <YOUR-JUPYTERHUB-TOKEN>" - wss://%h/user/<YOUR-JUPYTERHUB-USERNAME>/sshd/