Merge branch '4.4' into 5.1

* 4.4:
  Adopt src/.preload.php

Author: javiereguiluz

performance.rst

@@ -120,7 +120,7 @@ The preload file path is the same as the compiled service container but with the
 .. code-block:: ini
 
     ; php.ini
-    opcache.preload=/path/to/project/src/preload.php
+    opcache.preload=/path/to/project/src/.preload.php
 
 This file is generated by the ``cache:clear`` command.