Clarify automation example for Greenness night

[gcoan]

Updated the automation example to specify that the notification is for a Greenness night, and added a condition filter to only notify when the greenness score is at least 50.

[BottlecapDave]

Is there a reason you've expanded this automation? The automation examples are meant to be as small as possible and have only been added as a lot of people seem to unfamiliar with calendar triggers. To my knowledge with intelligent tariffs you get credit for charging on the greener nights, regardless what the index is (it could be 1).

I've fixed the automation intro on develop to not reference saving sessions.

[gcoan]

I primarily made the PR to fix the cut and paste error referring to saving session

Whilst I was at it, I made a small extension to the automation to show how people could have the automation trigger when specific greenness occurred. A good greenness score for example usually indicates low agile prices, and an alert every time there was a greenness event would be less useful.

Anyway, just a suggestion. People can always delete the condition if they don't want it