bug #4533 Add command to make symfony.phar executable. (xelaris)

This PR was submitted for the 2.7 branch but it was merged into the 2.3 branch instead (closes #4533).

Discussion
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Add command to make symfony.phar executable.

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets |

Commits
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dd9de4e Add command to make symfony.phar executable.

quick_tour/the_big_picture.rst

@@ -32,6 +32,7 @@ On **Linux** and **Mac OS X** systems, execute the following console commands:
 .. code-block:: bash
 
     $ curl -LsS http://symfony.com/installer > symfony.phar
+    $ chmod +x symfony.phar
     $ sudo mv symfony.phar /usr/local/bin/symfony
 
 .. note::
@@ -42,6 +43,7 @@ On **Linux** and **Mac OS X** systems, execute the following console commands:
     .. code-block:: bash
 
         $ php -r "readfile('http://symfony.com/installer');" > symfony.phar
+        $ chmod +x symfony.phar
         $ sudo mv symfony.phar /usr/local/bin/symfony
 
 After installing the Symfony installer, you'll have to open a new console window