add a rep leaderboard

Since my last reply, I had added the leaderboard, then I removed it and rejected the suggestion, but I'm re-adding a new version of the leaderboard. It's the best compromise I could've thought of.

https://appearance.guide/members/?key=reaction_score_past_month
I can change it to be the past 24hrs, past week, past month, past 6 months, past year, year-to-date, etc., but monthly sounds like a good starting point.