GUACAMOLE-470: Document new color-scheme parameter format for SSH and Telnet
GUACAMOLE-470: Document new color-scheme parameter format for SSH and Telnet

Document the new format of the color-scheme parameter with some
examples, for SSH and Telnet connections.

mike-jumper/incubator-guacamole-manual,mike-jumper/incubator-guacamole-manual,mike-jumper/incubator-guacamole-manual