League descriptions

A quick 'avoiding the hard work' update. I've added a 'description' to leagues so they can have a bit of a promotional blurb. (Another obvious-in-hindsight thing.) And in adding Team Black Diaspora Roller Derby I had to also loosen up the rule that Leagues needed to anchored to a place as they, like Team Indigenous Rising Roller Derby are global not just in one place.

As with the logo update, if you represent a league and want a description or logo added until I get the claim process finished, let me know and I can do it for you.