ITelnetTransport API documentation is incorrect for refusal case

[exarkun]

The do and will methods claim that the Deferred will fire with False if the option is refused. In fact, in the only implementation, the do Deferred will fire with OptionRefused and the will Deferred will probably errback with an AssertionError because of #4231.

The docs should be updated to reflect the implementation (not the reverse, since people might actually have depended on the currently implemented behavior).

[exarkun]

(In [30111]) Branching to 'telnet-transport-docs-4677'

[exarkun]

(In [30119]) Branching to 'telnet-transport-docs-4677-2'

[exarkun]

Simple doc changes in the branch, please review.

[therve]

Looks good, please merge.

[exarkun]

(In [30142]) Merge telnet-transport-docs-4677-2

Author: exarkun Reviewer: therve Fixes: #4677

Document a state tracking class internal to twisted.conch.telnet used for tracking the progress and results of telnet option negotiation. Also correct the interface documentation on ITelnetTransport to correctly describe the behavior in the case an option is refused.