fix nginx config error (#2562)

docker/nginx.conf

@@ -3,7 +3,7 @@ server {
     # gzip config
     gzip on;
     gzip_min_length 1k;
-    gzip_comp_level 9
+    gzip_comp_level 9;
     gzip_types text/plain application/javascript application/x-javascript text/css application/xml text/javascript application/x-httpd-php image/jpeg image/gif image/png;
     gzip_vary on;
     gzip_disable "MSIE [1-6]\.";