nginx: restart nginx on nginx.conf change

This also fixes the problem mentioned in the README.

playbooks/roles/nginx/tasks/main/config_deploy.yaml

@@ -26,6 +26,7 @@
         owner: root
         group: root
       become: true
+      notify: Restart `nginx.service`
 
 - name: handle the case, where no custom `nginx.conf` is to be used
   when: not nginx__use_custom_nginx_conf
@@ -41,6 +42,7 @@
         remote_src: true
         src: /etc/nginx/nginx.conf.ansiblesave
       become: true
+      notify: Restart `nginx.service`
 
     - name: delete the `nginx.conf.ansiblesave`, if it is present
       when: nginx__nginx_conf_ansiblesave_stat_result.stat.exists