doc: Remove Profile1.Cancel() method

doc: Remove Profile1.Cancel() method

There does not seem to be any actual need for this method.

The current implementation calls Cancel when a pending
NewConnection() or RequestDisconnection() method call fails.
Additionally it calls Cancel() when the remote client has disconnected.
In either case BlueZ calls shutdown on the file descriptor associated
with the agent and issues a Cancel() method call.

The closing of the file descriptor will trigger a HUP on the agent side,
which will trigger normal cleanup procedures.  The received Cancel()
method call is redundant in both cases.