nginx.conf: fix inconsistent client_max_body_size.

config/danbooru_default_config.rb

@@ -187,7 +187,8 @@ module Danbooru
       1_000
     end
 
-    # Maximum size of an upload.
+    # Maximum size of an upload. If you change this, you must also change
+    # `client_max_body_size` in your nginx.conf.
     def max_file_size
       35.megabytes
     end

script/install/nginx.danbooru.conf

@@ -7,7 +7,7 @@ server {
   index index.html;
   access_log /var/log/nginx/danbooru.access.log;
   error_log /var/log/nginx/danbooru.error.log;
-  client_max_body_size 30m;
+  client_max_body_size 35m;
   location /stylesheets {
     expires max;
     break;