minor #11293 [Setup] Defer the removal of bundle directory (phansys)

This PR was submitted for the master branch but it was merged into the 4.2 branch instead (closes #11293).

Discussion
----------

[Setup] Defer the removal of bundle directory

Currently, the bundle directory is still referenced after the step where the removal instruction is placed.

Commits
-------

a0eabfa [Setup] Defer the removal of bundle directory

Author: javiereguiluz

setup/flex.rst

@@ -239,7 +239,7 @@ manual steps:
 
 #. Move the original PHP source code from ``src/AppBundle/*``, except bundle
    specific files (like ``AppBundle.php`` and ``DependencyInjection/``), to
-   ``src/``. Remove ``src/AppBundle/``.
+   ``src/``.
 
    In addition to moving the files, update the ``autoload`` and ``autoload-dev``
    values of the ``composer.json`` file as `shown in this example`_ to use
@@ -265,6 +265,8 @@ manual steps:
 #. Update the ``bin/console`` script `copying Symfony's bin/console source`_
    and changing anything according to your original console script.
 
+#. Remove ``src/AppBundle/``.
+
 #. Remove the ``bin/symfony_requirements`` script and if you need a replacement
    for it, use the new `Symfony Requirements Checker`_.