how do we add a course?

[ultrasaurus]

It used to be via pull request, but it looks like the data has been moved to the database. Would be good to add some help text here:

Can someone add some detail on how this works now?

[tjgrathwell]

The procedure is still to add it with code, they're in the database so we can hypothetically add some UI to add courses later.

The last time a course was added it looked like this: b8ea7d2. After a course is added to that file and deployed, someone needs to run rake populate_courses, which is currently documented to "only run once" but actually should be idempotent.

[ultrasaurus]

note for docs: if someone removes a level, it doesn't actually get removed. So, prolly better not to do that right now.