Add average temp label

[aaravrav]

Is there an existing issue for this?

• [x] I have searched the existing issues

Describe the solution you'd like

Alongside the temperature, and the highest temperature, an average temperature label would be useful

[nokyan]

Hi, the "Highest" label was supposed to be a temporary workaround for me not figuring out how to cleanly make the highest value readable on the graph itself. Therefore I'm not currently considering implementing an average temperature label, I'm afraid.

[aaravrav]

So is this not technically easy to implement? I find average temp the most useful metric when monitoring the...temp