Meetup
- A user can now delete their raid via the bot's interface, so they won't need the manage message permission.
- There is a new command !meetup that is similar to the raid command but does not take a tier argument.
- The boss field is now empty by default instead of 'All'.
- A bugfix for when the bot crashed if you tried to update your raid with an invalid tier.
- Added a command overview to the README.