Fix rate limiter configuration

Dockerfile

@@ -1,6 +1,7 @@
 # Install Caddy
 FROM docker.io/caddy:builder-alpine AS caddy-builder
-RUN xcaddy build
+RUN xcaddy build \
+    --with github.com/mholt/caddy-ratelimit
 
 
 # Install PHP

config/Caddyfile

@@ -6,6 +6,17 @@
 }
 
 :8080 {
+    rate_limit {
+        distributed
+        zone dynamic {
+            key    {client_ip}
+            events 20
+            window 5s
+            jitter 0.1
+        }
+        log_key
+    }
+
     root * /phpbb/www
 
     php_fastcgi unix//run/php-fpm.sock {