In NR with several layers, we may have MAC PDU of size bigger than 64KB,
which does not fit into a UDP buffer, destroying macpdu2wireshark.
Let's add an option to dump to a pcap file instead of using UDP packets.
The DLT 252 magic is used (check wireshark documentation to understand).
Run macpdu2wireshark with -h to see how to configure wireshark to read
the produced files.
* the goal is to make the documentation more procedural and
descriptive and easier to understand
* added missing info in RLC-NR about reassembling of AM frames
Cedric Roux