Clarify how "helpful issues" are calculated

[warflash]

Based on the description (3+ reactions) I think this metric isn't quite working yet or I am misunderstanding what reactions are in this case. Personally I've opened issues that recieved 3+ emote reactions and/or 3+ comments but the api returns 0 points which I find odd based on the description.

As a sidenote: I think it'd be nice to maybe do (3+ reactions OR 5+ comments) for an issue to count as helpful, assuming currently it's only checking emotes. I feel like many people on github don't use emotes and an issue that sparked a discussion instead would be of roughly equal value imo