Document graphs

[SevereOverfl0w]

How do I create a graph like the one described in the README? #tagged=climbing #since=30d #plot=done. Maybe I am misunderstanding what it means.

[abhizen]

I also did not get this part. I tried typing #since=15d #plot=done but the command just gives two parallel lines

[questor]

The both parallel lines are an empty sparkline, I assume you have to set the due-date for a task to see something, but I have no idea how to set the due-date. I think it's a special format in the title, but I have no idea how this format needs to look like.