minor #1490 Update README.rst (Narno)

This PR was squashed before being merged into the 2.1.x-dev branch (closes #1490).

Discussion
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Update README.rst

Add code-bloc for PHP and delete `$` before command lines.

Commits
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c98f3529 Update README.rst

README.rst

@@ -2,7 +2,9 @@ Silex, a simple Web Framework
 =============================
 
 Silex is a PHP micro-framework to develop websites based on `Symfony
-components`_::
+components`_:
+
+.. code-block:: php
 
     <?php
 
@@ -42,8 +44,8 @@ To run the test suite, you need `Composer`_ and `PHPUnit`_:
 
 .. code-block:: bash
 
-    $ composer install
-    $ phpunit
+    composer install
+    phpunit
 
 Community
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