Add ApexCharts configuration to README

[rany2]

Credit to @elRadix, I have permission to add it to the README
See https://community.home-assistant.io/t/open-meteo-solar-forecast/733073/133?u=rany

[rany2]

Make sure to add this suggestion by @andreas-bulling: https://community.home-assistant.io/t/open-meteo-solar-forecast/733073/136?u=rany

Without it the graph is more difficult to read (it shows a dotted red vertical line that tells you were you are in the graph right now).

[rany2]

Also I'll use watts attribute not wh_period, I'm not sure why everyone settled on the latter....

[andreas-bulling]

I can only speak for myself but the reason is that these are all estimates after all, i.e. they have error. What's the point in showing more fine-grained estimates (and errors) in this case?

[rany2]

For me it's mostly aesthetics, there's obviously no real advantage besides a smoother looking graph. wh_period looks more rough. If there is a technical reason to use wh_period instead, I'd be interested to hear it.