Added missing step to transitioning squashed migrations.

of your application, making sure that they run ``migrate`` to store the change

in their database.

After this has been done, you must then transition the squashed migration to

a normal initial migration, by:

You must then transition the squashed migration to a normal migration by:

- Deleting all the migration files it replaces

- Removing the ``replaces`` argument in the ``Migration`` class of the

  squashed migration (this is how Django tells that it is a squashed migration)

- Deleting all the migration files it replaces.

- Updating all migrations that depend on the deleted migrations to depend on

  the squashed migration instead.

- Removing the ``replaces`` attribute in the ``Migration`` class of the

  squashed migration (this is how Django tells that it is a squashed migration).

.. note::

    Once you've squashed a migration, you should not then re-squash that squashed