Add router metrics

docs/content/reference/static-configuration/env-ref.md

@@ -231,6 +231,9 @@ Enable metrics on entry points. (Default: ```true```)
 `TRAEFIK_METRICS_DATADOG_ADDRESS`:  
 Datadog's address. (Default: ```localhost:8125```)
 
+`TRAEFIK_METRICS_DATADOG_ADDROUTERSLABELS`:  
+Enable metrics on routers. (Default: ```false```)
+
 `TRAEFIK_METRICS_DATADOG_ADDSERVICESLABELS`:  
 Enable metrics on services. (Default: ```true```)
 
@@ -246,6 +249,9 @@ Enable metrics on entry points. (Default: ```true```)
 `TRAEFIK_METRICS_INFLUXDB_ADDRESS`:  
 InfluxDB address. (Default: ```localhost:8089```)
 
+`TRAEFIK_METRICS_INFLUXDB_ADDROUTERSLABELS`:  
+Enable metrics on routers. (Default: ```false```)
+
 `TRAEFIK_METRICS_INFLUXDB_ADDSERVICESLABELS`:  
 Enable metrics on services. (Default: ```true```)
 
@@ -273,6 +279,9 @@ Prometheus metrics exporter type. (Default: ```false```)
 `TRAEFIK_METRICS_PROMETHEUS_ADDENTRYPOINTSLABELS`:  
 Enable metrics on entry points. (Default: ```true```)
 
+`TRAEFIK_METRICS_PROMETHEUS_ADDROUTERSLABELS`:  
+Enable metrics on routers. (Default: ```false```)
+
 `TRAEFIK_METRICS_PROMETHEUS_ADDSERVICESLABELS`:  
 Enable metrics on services. (Default: ```true```)
 
@@ -294,6 +303,9 @@ Enable metrics on entry points. (Default: ```true```)
 `TRAEFIK_METRICS_STATSD_ADDRESS`:  
 StatsD address. (Default: ```localhost:8125```)
 
+`TRAEFIK_METRICS_STATSD_ADDROUTERSLABELS`:  
+Enable metrics on routers. (Default: ```false```)
+
 `TRAEFIK_METRICS_STATSD_ADDSERVICESLABELS`:  
 Enable metrics on services. (Default: ```true```)