Add more details to "Events" page

https://about.bostonpython.com/events

For example:

- How to propose a talk
- How events get announced
- How RSVPs work
- What to expect at the event (e.g. pizza, greetings, announcements)
- Common tables at project night
- What "project night" means (i.e., you don't need a project)
- Photos/videos
- List of upcoming events (maybe via the Meetup API)