Fixed some missing references

Author: javiereguiluz

best_practices/creating-the-project.rst

@@ -91,5 +91,6 @@ Symfony applications can still use third-party bundles (installed in ``vendor/``
 to add features, but you should use PHP namespaces instead of bundles to organize
 your own code.
 
-.. _`Symfony Skeleton`: https://github.com/symfony/skeleton
 .. _`Composer`: https://getcomposer.org/
+.. _`Symfony Flex`: https://github.com/symfony/flex
+.. _`Symfony Skeleton`: https://github.com/symfony/skeleton