Transport: Incoporate feedback from Steve Huston's review (2)

Update the transport part of the specification in response to the following comments from Steve's review:

Part 2, sect 1, 1st sentence: Replace "The" with "An" (there isn't just
one AMQP network). Same correction in 3rd para, 1st sentence; also in 5th
para, 1st sentence.

Part 2, sect 1, 2nd para, 2nd sentence: should be "Each link attaches to a
node at a terminus."

Part 2, section 1, 4th para. Replace with "Nodes exist within a container.
A container is either a broker or a client application. Each container may
hold many nodes. Examples of AMQP nodes are producers, consumers, and
queues. Producers and consumers are the elements within a client
application that generate and process messages. Queues are entities within
a broker that store and forward messages."
Q on this... do queues only exist in brokers? Do brokers ever
produce/consume messages? The URL diagram implies no such restriction.

Part 2, section 4.5, 5th para, 2nd sentence: Replace "can" with "MUST" or
"may" (if it's not a protocol requirement).

Part 2, section 7.1, ... should maybe cross reference section 4.3 to
clarify the intention is to close the AMQP connection, not the TCP
connection (at least immediately).