minor symfony#9416 Ask users to create two commits for reproducers (javiereguiluz)

This PR was squashed before being merged into the 2.7 branch (closes symfony#9416).

Discussion
----------

Ask users to create two commits for reproducers

Fixes symfony#9365 proposed by @ro0n.

Commits
-------

2682799 Ask users to create two commits for reproducers

Author: javiereguiluz

contributing/code/reproducer.rst

@@ -42,9 +42,10 @@ edition. To do so:
    ``git clone git://github.com/YOUR-GITHUB-USERNAME/symfony-standard.git``
 #. Browse the project and create a new branch (e.g. ``issue_23567``,
    ``reproduce_23657``, etc.)
+#. Add and commit the changes generated by Symfony.
 #. Now you must add the minimum amount of code to reproduce the bug. This is the
    trickiest part and it's explained a bit more later.
-#. Add, commit and push all your changes.
+#. Add, commit and push all your own changes.
 #. Add a comment in your original issue report to share the URL of your forked
    project (e.g. ``https://github.com/YOUR-GITHUB-USERNAME/symfony-standard/tree/issue_23567``)
    and, if necessary, explain the steps to reproduce (e.g. "browse this URL",