Merge branch '5.1' into 5.2

* 5.1:
  Update the Nginx example

Author: javiereguiluz

setup/web_server_configuration.rst

@@ -334,6 +334,9 @@ The **minimum configuration** to get your application running under Nginx is:
             # Otherwise, PHP's OPcache may not properly detect changes to
             # your PHP files (see https://github.com/zendtech/ZendOptimizerPlus/issues/126
             # for more information).
+            # Caveat: When PHP-FPM is hosted on a different machine from nginx
+            #         $realpath_root may not resolve as you expect! In this case try using
+            #         $document_root instead.
             fastcgi_param SCRIPT_FILENAME $realpath_root$fastcgi_script_name;
             fastcgi_param DOCUMENT_ROOT $realpath_root;
             # Prevents URIs that include the front controller. This will 404: