Documentation: better description of the network testing procedure for sim

[btashton]

For the sim:nettest target it fails. This could very easily be an issue not configuring the environment correctly, but there is no documentation in the readme about what needs to be setup if anything. Is probably does not need to be a blocker, but we need to document how this works

❯ ./nuttx 
[sudo] password for bashton: 
Connecting to Address: 0100000a
client: connect failure: 114

[btashton]

This looks like it also impacts sim:pktradio sim:sixlowpan which I would expect to work as well, so I have moved this to blocker.

pktradio:

nsh> nettest
Binding to Address: 80fe:0000:0000:0000:0000:ff00:00fe:a900
server: Accepting connections on port 61616
Connecting to Address: 80fe:0000:0000:0000:0000:ff00:00fe:a900
client: connect failure: 116

sixlowpan:

nsh> nettest
Binding to Address: 80fe:0000:0000:0000:0000:ff00:00fe:a9cd
server: Accepting connections on port 61616
Connecting to Address: 80fe:0000:0000:0000:0000:ff00:00fe:a9cd
client: connect failure: 116

[btashton]

I am going to remove this from being a release blocker, but I am going to leave the ticket up for documentation. We really need to improve the testing documentation around the network system. There are a lot of tools and knobs but little of it is in the new docs and how to use the debug apps is hidden in the readmes and code.

As far as I can tell this mostly "works" now once you get the environment setup. So feel fine for this release at least.