Merge branch '4.4' into 5.1

* 4.4:
  Tweak
  Update using_components.rst
  Add documentation about impersonating users with an HTTP Header

Author: javiereguiluz

components/using_components.rst

@@ -20,7 +20,7 @@ Using the Finder Component
 
 **1.** If you're creating a new project, create a new empty directory for it.
 
-**2.** Open a terminal and use Composer to grab the library.
+**2.** Open a terminal, step into this directory and use Composer to grab the library.
 
 .. code-block:: terminal
 
@@ -43,18 +43,26 @@ the ``vendor/autoload.php`` file that was generated by Composer. This file
 takes care of autoloading all of the libraries so that you can use them
 immediately::
 
-    // File example: src/script.php
-
-    // update this to the path to the "vendor/"
-    // directory, relative to this file
+    // Project structure example:
+    // my_project/
+    //     data/
+    //         ...              # Some project data
+    //     src/
+    //         my_script.php    # Main entry point
+    //     vendor/
+    //         autoload.php     # Autoloader generated by Composer
+    //         ...              # Packages downloaded by Composer
+
+    // File example: src/my_script.php
+    // Autoloader relative path to this PHP file
     require_once __DIR__.'/../vendor/autoload.php';
 
     use Symfony\Component\Finder\Finder;
 
     $finder = new Finder();
     $finder->in('../data/');
 
-    // ...
+    // rest of your PHP code...
 
 Now what?
 ---------

security/impersonating_user.rst

@@ -74,6 +74,11 @@ as the value to the current URL:
 
     http://example.com/somewhere?_switch_user=thomas
 
+.. tip::
+
+    Instead of adding a ``_switch_user`` query string parameter, you can pass
+    the username in a ``HTTP_X_SWITCH_USER`` header.
+
 To switch back to the original user, use the special ``_exit`` username:
 
 .. code-block:: text