With regard to #179, we need to update the path to Zephyr binary in Renode.
It is not copy-paste ready, but now it's evident.
Unfortunately Renode does not have an option to reference $HOME.
Following all the instructions in order leaves you with python3.6 from
the TOMU toolchain first in your PATH, which doesn't work for building
zephyr.
Add a note to remove it from your PATH.