It allows any label, but then complains that “You specified the invalid choice X”. So what are allowable values for X?
I was searching the same issue but couldn’t find anything. Hope someone who knows can help us!
Problem is still open.
To define a configuration-field like “dashboard general tab activity metrics” without documentation seems somewhat stupid to me.
Maybe there are no other options than the predefined ones. But then: why make it configurable at all?
So you can remove specific metrics from the dashboard.
I found the file which defines the allowed options: discourse/site_settings.yml at fde9e6bc25227b69195181d45ee4360c25c279da · discourse/discourse · GitHub