[feature] Make rate limit requests amount configurable (#966)

* update rate limit documentation

* regenerate landingpage config helpers

* make rate limit rate configurable

docs/configuration/advanced.md

@@ -35,4 +35,21 @@ These are set to sensible defaults, so most server admins won't need to touch th
 # Options: ["lax", "strict"]
 # Default: "lax"
 advanced-cookies-samesite: "lax"
+
+# Int. Amount of requests to permit from a single IP address within a span of 5 minutes.
+# If this amount is exceeded, a 429 HTTP error code will be returned.
+# See https://docs.gotosocial.org/en/latest/api/swagger/#rate-limit.
+#
+# If you find yourself adjusting this limit because it's regularly being exceeded,
+# you should first verify that your settings for `trusted-proxies` (above) are correct.
+# In many cases, when the rate limit is exceeded it is because your instance sees all
+# incoming requests as coming from the *same IP address* (you can verify this by looking
+# at the client IPs in your instance logs). If this is the case, try adding that IP
+# address to your `trusted-proxies` *BEFORE* you go adjusting this rate limit setting!
+#
+# If you set this to 0 or less, rate limiting will be disabled entirely.
+#
+# Examples: [1000, 500, 0]
+# Default: 1000
+advanced-rate-limit-requests: 1000
 ```