minor #4352 [Best Practices] update best practices index (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

[Best Practices] update best practices index

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

This way, the table of contents on the index page has only one level
like every other index in the documentation.

Commits
-------

facea46 update best practices index

Author: weaverryan

Diff for: best_practices/index.rst

@@ -2,6 +2,7 @@ Official Symfony Best Practices
 ===============================
 
 .. toctree::
+    :hidden:
 
     introduction
     creating-the-project
@@ -14,3 +15,5 @@ Official Symfony Best Practices
     security
     web-assets
     tests
+
+.. include:: /best_practices/map.rst.inc

Diff for: best_practices/map.rst.inc

@@ -0,0 +1,11 @@
+* :doc:`/best_practices/introduction`
+* :doc:`/best_practices/creating-the-project`
+* :doc:`/best_practices/configuration`
+* :doc:`/best_practices/business-logic`
+* :doc:`/best_practices/controllers`
+* :doc:`/best_practices/templates`
+* :doc:`/best_practices/forms`
+* :doc:`/best_practices/i18n`
+* :doc:`/best_practices/security`
+* :doc:`/best_practices/web-assets`
+* :doc:`/best_practices/tests`