Upcoming sessions on the playgroup overview, and deeper metagame notes

The playgroup overview page now shows your next few upcoming Planner sessions right at the top, with the date, location, format, and how many people have confirmed. Click through to the Planner for the full sign-up list, or to schedule one if nothing's on the calendar yet. The official format pages (Standard, Modern, Pioneer, Legacy, Pauper, Vintage, and Commander) also got a deeper metagame writeup, naming actual archetype families instead of a generic one-liner — things like Amulet Titan and Yawgmoth for Modern, or Rakdos Sacrifice and Mono-Green Devotion for Pioneer.