Restore some wrongly removed contents

Author: javiereguiluz

components/phpunit_bridge.rst

@@ -839,6 +839,11 @@ its ``bin/simple-phpunit`` command. It has the following features:
   this directory for ``phpunit.xml.dist`` files up to ``SYMFONY_PHPUNIT_MAX_DEPTH``
   levels (specified as an env var, defaults to ``3``);
 
+The script writes the modified PHPUnit it builds in a directory that can be
+configured by the ``SYMFONY_PHPUNIT_DIR`` env var, or in the same directory as
+the ``simple-phpunit`` if it is not provided. It's also possible to set this
+env var in the ``phpunit.xml.dist`` file.
+
 If you have installed the bridge through Composer, you can run it by calling e.g.:
 
 .. code-block:: terminal