Calculate total participation moments by month using Data Explorer

[rishabh]

We can accept PRs to add queries, here’s an example:

https://github.com/discourse/discourse-data-explorer/pull/43

Besides that, What cool data explorer queries have you come up with? and @SidV’s list https://github.com/SidVal/discourse-data-explorer/blob/queries/querys.md have a ton of useful queries too!