Document high level generic information about what binding means and how / why you would bind a service to a mobile client.

ping Peter Braun As requested by John F

To land as per https://docs.google.com/a/redhat.com/document/d/1vT9LjMyGYIiBu6w8xUnWQ6eISvGHFXx_aqetZrp7M1I/edit?disco=AAAAB_xTRT8