doc: announce ethdev ABI change for LRO fields

doc: announce ethdev ABI change for LRO fields

It may be needed by the user to limit the LRO session packet size.
In order to allow the above limitation, a new Rx configuration may be
added for the maximum LRO session size.

A new capability may be added too to expose the maximum LRO session size
supported by the port.

Signed-off-by: Matan Azrad <matan@mellanox.com>
Acked-by: Andrew Rybchenko <arybchenko@solarflare.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>