Document ztag data flow

[zakird]

1. what data is updated by different pieces
2. how port / protocol / subprotocol all fit together within the context of zdb

[elnappo]

I want to contribute to ztag especially into the ICS parts, but the leak of documentation makes it hard to start. Could you please add some essential documentation and how to run ztag in combination with zmap and zgrab locally? Or did I miss something?
Thank you!