Document default discourse_docker nginx-level rate limits

It took a while to find them, but our install followed the rate-limits on nginx specified here: discourse_docker/web.ratelimited.template.yml at 8e413bd571538f65e9642641ddf332534f0296b0 路 discourse/discourse_docker 路 GitHub

These are above the rest set using env variables set in the app.yml container config (which are already hard to find from the main Discourse API docs :slight_smile:), but as we can see from the defaults, the nginx config is stringent enough to become the limiting rate if the default MAX_ADMIN_API_REQUESTS_PER_MINUTE is > 200.
They are easy enough to change, but it would be nice to compile documentation to know where the defaults are for a given topic such as rate-limiting.