Clarifying the use of message_seq vs. record sequence_number

[ekr]

Copied from ekr's repo:
Ben wrote:

On page 20, second paragraph, please be clear that it is the
message_seq vs. the record sequence_number that must match
next_receive_seq.
The text in the document says:

DTLS implementations maintain (at least notionally) a
next_receive_seq counter. This counter is initially set to zero.
When a message is received, if its sequence number matches
next_receive_seq, next_receive_seq is incremented and the message is
processed. If the sequence number is less than next_receive_seq, the
message MUST be discarded. If the sequence number is greater than
next_receive_seq, the implementation SHOULD queue the message but MAY
discard it. (This is a simple space/bandwidth tradeoff).