Update build instructions for direwolf 1.6

Also reduce build size, run a docker user, give it a place to log

DWARGS

Set to add/pass any arguments to the direwolf executable, example -t 0 for no color logs

DW_STANDALONE for Digipeaters

Optionally start direwolf without rtl_fm as input

v1.0.0

• Customizable Environment Variables
• GitHub Actions automate build & publish to Docker Hub