Added rfc-editor note to break draft

[Sam Hartman <hartmans-ietf%mit.edu@localhost>]

Hi.  The break draft is on this week's IESG agenda for review and
possible approval.

One of the ADs noted that the first reference to the ssh channel
protocol is unqualified.  I added an RFC editor note (instructions to
rfc editor on textual changes to apply during publication) adding such
a reference.

--Sam