Added upgrade instructions for 1.8.0

doc/upgrade.rst

@@ -167,6 +167,52 @@ Don't forget to run the following command:
 
    > python manage.py collectstatic
 
+1.8.0
+=====
+
+Modoboa now relies on `Django's builtin password validation system
+<https://docs.djangoproject.com/en/1.10/topics/auth/passwords/#module-django.contrib.auth.password_validation>`_
+to validate user passwords, instead of ``django-passwords``.
+
+Remove ``django-passwords`` from your system:
+
+.. sourcecode:: bash
+
+   > sudo -u <modoboa_user> -i
+   > source <virtuenv_path>/bin/activate
+   > pip uninstall django-passwords
+
+Then, edit the :file:`settings.py` file and add the following content
+inside::
+
+.. sourcecode:: python
+
+   # Password validation rules
+
+   AUTH_PASSWORD_VALIDATORS = [
+       {
+           'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
+       },
+       {
+           'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
+       },
+       {
+           'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
+       },
+       {
+           'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
+       },
+       {
+           'NAME': 'modoboa.core.password_validation.ComplexityValidator',
+           'OPTIONS': {
+               'upper': 1,
+               'lower': 1,
+               'digits': 1,
+               'specials': 0
+           }
+       },
+   ]
+
 1.7.1
 =====