Commit e301f1a8ed11f9eacb2b7f525a7446dc00621a8b removed the NGINX argument
entirely, but users may rely on and override it. Reported by rekado on #guix.
* gnu/services/monitoring.scm (%zabbix-front-end-nginx-configuration): Restore
exported variable.
(zabbix-front-end-nginx-extension): New procedure.
(zabbix-front-end-configuration): Remove FASTCGI-PARAMS field. Restore NGINX
field, but default to the empty list.
(zabbix-front-end-service-type): Extend NGINX-SERVICE-TYPE by
ZABBIX-FRONT-END-NGINX-EXTENSION.
* doc/guix.texi (Monitoring Services): Regenerate documentation.
326e08bf0f