[subexp-daq] drasi trigger bus and data flow options

[Håkan T Johansson]

Hi!

A long while ago, I think there was a question about the relationships of 
various options in drasi related to data flow and the trigger bus.

The documentation now has two pictures to illustrate:

https://fy.chalmers.se/~f96hajo/drasi/doc/drasi_buffers.html

https://fy.chalmers.se/~f96hajo/drasi/doc/drasi_trigbus.html

Cheers,
Håkan