Add note for Mac Tunnelblick client configuration

[john-flagship]

Needed to add an arbitrary prefix to the hostname in the ovpn file in order for RDP client to connect (and for routing to work properly)

[john-flagship]

Note that one successful RDP connection is no indicator of another!

I don't know if this is a Tunnelblick thing or what but there have been instances where I needed to disconnect and quit Tunnelblick multiple times before I RDP would work (note that Tunnelblick connects to the VPN just fine but traffic isn't routing).

This doesn't fall on you or the blueprint but wanted to make you aware