Docker build system

[peteruithoven]

Inspired by the openwrt buildroot system I created earlier and following some of @ joostn's dockerfile commands I created a LaOS firmware builder:
https://github.com/peteruithoven/Firmware-builder

I'm curious what you guys think.
We could add a link to the Readme?

[jrv]

Fine by me. Alternatively, you could add the dockerfile + readme in a subfolder of the Firmware (avoiding yet another repository).