Fix an error in examples

Add the grain='os' parameter into map.jinja.
Refer to https://github.com/saltstack-formulas/samba-formula/blob/2727dfb0922768bdea6669e37782919ad9c4c545/samba/map.jinja
Unfortunately https://github.com/saltstack-formulas/apache-formula/blob/2db91119af17f780f5901e5d72f9d9dfc891658b/apache/map.jinja has the same error.
Maybe author of apache-formula has some custom configuration or modules hacked.