minor #6066 Update location of app/check.php to bin/symfony_requirements (Kevinrob)

This PR was merged into the 3.0 branch.

Discussion
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Update location of `app/check.php` to `bin/symfony_requirements`

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 3.0
| Fixed tickets | -

Commits
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d33d77a Update location of `app/check.php` to `bin/symfony_requirements`

Author: xabbuh

reference/requirements.rst

@@ -14,7 +14,7 @@ your requirements from the command line via:
 
 .. code-block:: bash
 
-    $ php app/check.php
+    $ php bin/symfony_requirements
 
 Below is the list of required and optional requirements.