feature #4425 Updating component usage to use composer require (weaverryan)

This PR was merged into the 2.3 branch.

Discussion
----------

Updating component usage to use composer require

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3+
| Fixed tickets | n/a

Hi guys!

This shows using the new `composer require` command instead of manually updating `composer.json`. It shortens and simplifies things quite a bit 😀

Thanks!

Commits
-------

d64fae2 Adding details about a specific version
8a50c9c Updating component usage to use composer require

Author: weaverryan

components/using_components.rst

@@ -20,40 +20,39 @@ Using the Finder Component
 
 **1.** If you're creating a new project, create a new empty directory for it.
 
-**2.** Create a new file called ``composer.json`` and paste the following into it:
+**2.** Open a terminal and use Composer to grab the library.
 
-.. code-block:: json
+.. code-block:: bash
 
-    {
-        "require": {
-            "symfony/finder": "2.3.*"
-        }
-    }
+    $ composer require symfony/finder
 
-If you already have a ``composer.json`` file, just add this line to it. You
-may also need to adjust the version (e.g. ``2.2.2`` or ``2.3.*``).
+The name ``symfony/finder`` is written at the top of the documentation for
+whatever component you want.
 
-You can research the component names and versions at `packagist.org`_.
+.. tip::
 
-**3.** `Install composer`_ if you don't already have it present on your system:
+    If you get a command not found for ``composer``, you'll need to
+    `Install composer`_. Depending on how you install, you may end up with
+    a ``composer.phar`` file in your directory. In that case, no worries!
+    Just run ``php composer.phar require symfony/finder``.
 
-**4.** Download the vendor libraries and generate the ``vendor/autoload.php`` file:
+If you know you need a specific version of the library, add that to the command:
 
 .. code-block:: bash
 
-    $ php composer.phar install
+    $ composer require symfony/finder:~2.3
 
-**5.** Write your code:
+**3.** Write your code!
 
 Once Composer has downloaded the component(s), all you need to do is include
 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: src/script.php
+    // File example: src/script.php
 
     // update this to the path to the "vendor/" directory, relative to this file
-    require_once '../vendor/autoload.php';
+    require_once __DIR__.'../vendor/autoload.php';
 
     use Symfony\Component\Finder\Finder;
 
@@ -62,33 +61,18 @@ immediately::
 
     // ...
 
-.. tip::
-
-    If you want to use all of the Symfony Components, then instead of adding
-    them one by one:
+Using all of the Components
+---------------------------
 
-    .. code-block:: json
+If you want to use all of the Symfony Components, then instead of adding
+them one by one, you can include the ``symfony/symfony`` package:
 
-        {
-            "require": {
-                "symfony/finder": "2.3.*",
-                "symfony/dom-crawler": "2.3.*",
-                "symfony/css-selector": "2.3.*"
-            }
-        }
-
-    you can use:
-
-    .. code-block:: json
+.. code-block:: bash
 
-        {
-            "require": {
-                "symfony/symfony": "2.3.*"
-            }
-        }
+    $ composer require symfony/symfony
 
-    This will include the Bundle and Bridge libraries, which you may not
-    actually need.
+This will also include the Bundle and Bridge libraries, which you may or
+may not actually need.
 
 Now what?
 ---------
@@ -100,4 +84,3 @@ And have fun!
 
 .. _Composer: http://getcomposer.org
 .. _Install composer: http://getcomposer.org/download/
-.. _packagist.org: https://packagist.org/