GPIO Bindings, documentation feedback


I just installed the GPIO binding using the apt-get method.
I edited etc/default/openhab and set following:

as the documentation says.

After this, openhab refused to start with the following error :[20155]: Invalid Configuration LocationThe configuration area at ‘/var/lib/openhab/workspace’ is not writable.
(I use systemctl for starting openhab)

To fix it, I had to edit /usr/lib/systemd/system/openhab.service and set user and group to root.
I am not sure if its correct, if it is, the doc should probably be updated with it.

Please add this to the wiki page. What you did looks reasonable and correct.