Documentation needed

[Redsandro]

Could you expand on the documentation a bit? What steps you take to make it run?

In my case the HDD temps seem to be stuck. hddtemp on the shell varies, but the values in Grafana (using Prometheus) stay static. I probably missed a step.

[webvictim]

I actually think I have this same problem and 'solved' it by just restarting the sensor-exporter container every 5 minutes so that it logs a new data point. It'd be nice to figure out why it isn't polling hddtemp, though.

[martivo]

I have fixed the issue wiht hddtemp - it was not working correctly. You can find the code changed from here #4

[Redsandro]

@mardicas could you turn this into a PR?

[martivo]

Done in #5