Update of the installation documentation

I updated the documentation to fit the new name of the migration script.
Signed-off-by: Matthieu Berjon <matthieu.berjon@inria.fr>

django/docs/installation.rst

@@ -37,7 +37,7 @@ Development
 .. code-block:: bash
   
   # Dump the tables from Allgo rails and import them into Allgo Django
-  ./tools/migration-db.sh --init
+  ./tools/migration.sh --init
 
   # Run the Django webserver
   python manage.py runserver