suggestion for README-rpi3-liquidsoap

[nickajeglin]

I just set up liquidsoap-->icecast2, and the readme might benefit from a couple of small additions.

1. Instruct people to set the log level 3 in op25.liq.
   I'm guessing lots of people will get complaints from liquidsoap about fdkaac since it isn't in the raspbian repos and think that liquidsoap hangs since log 1 stops there. Alternatively, you could just increase the default log level to 3 in the original file

2. Note that if you have op25.sh already working, you need to remove the -U parameter in addition to adding the -w. It's easy to miss. Ie.:
   "(In particular note the removal of -U and the new -w parameter, that allows liquid to connect)"

3. Note that to test if liquidsoap-->icecast2 is working you must go to http://192.168.0.#:8000/op25 instead of just http://192.168.0.#:8000 (or localhost, or what have you).
   Having never used icecast before, I spent a lot of time troubleshooting something that was already working because I didn't realize that I needed to navigate to the actual mount point.

[W3AXL]

+1 on item 2 above, I spent a good 20 minutes trying to figure out why my liquidsoap audio wasn't working before I stumbled upon this issue for the solution.