This patch against stable/13 documents fixes several issues related to the `trpt` utility including:
- Fix the computation of the TCP payload bytes, in particular when TCP options are present or IPv4 is used.
- Fix the logging of incoming packets.
- Improve the logging of outgoing packets.
- Fix the logging of timers, in particular add support for logging of the delayed ack timer.
Also add a deprecation note, since support for this utility has been removed from the main branch. Therefore, this will be a direct commit to stable/13.