Add missing variable to template.env

Author: mrnicegyu11

services/maintenance-page/template.env

@@ -3,6 +3,7 @@ DEPLOYMENT_FQDNS=${DEPLOYMENT_FQDNS}
 API_DOMAIN='${API_DOMAIN}'
 DEPLOYMENT_API_DOMAIN_CAPTURE_TRAEFIK_RULE='${DEPLOYMENT_API_DOMAIN_CAPTURE_TRAEFIK_RULE}'
 DEPLOYMENT_FQDNS_CAPTURE_TRAEFIK_RULE_MAINTENANCE_PAGE='${DEPLOYMENT_FQDNS_CAPTURE_TRAEFIK_RULE_MAINTENANCE_PAGE}'
+DEPLOYMENT_FQDNS_CAPTURE_INVITATIONS='${DEPLOYMENT_FQDNS_CAPTURE_INVITATIONS}'
 PUBLIC_NETWORK=${PUBLIC_NETWORK}
 MONITORED_NETWORK=${MONITORED_NETWORK}
 REPO_CONFIG_LOCATION=${REPO_CONFIG_LOCATION}