Support Consul KV Enterprise namespaces

Co-authored-by: Romain <rtribotte@users.noreply.github.com>

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

@@ -351,6 +351,9 @@ Enable Consul backend with default settings. (Default: ```false```)
 `--providers.consul.endpoints`:  
 KV store endpoints (Default: ```127.0.0.1:8500```)
 
+`--providers.consul.namespace`:  
+KV Namespace
+
 `--providers.consul.password`:  
 KV Password
 
@@ -534,6 +537,9 @@ Enable Etcd backend with default settings. (Default: ```false```)
 `--providers.etcd.endpoints`:  
 KV store endpoints (Default: ```127.0.0.1:2379```)
 
+`--providers.etcd.namespace`:  
+KV Namespace
+
 `--providers.etcd.password`:  
 KV Password
 
@@ -789,6 +795,9 @@ Enable Redis backend with default settings. (Default: ```false```)
 `--providers.redis.endpoints`:  
 KV store endpoints (Default: ```127.0.0.1:6379```)
 
+`--providers.redis.namespace`:  
+KV Namespace
+
 `--providers.redis.password`:  
 KV Password
 
@@ -825,6 +834,9 @@ Enable ZooKeeper backend with default settings. (Default: ```false```)
 `--providers.zookeeper.endpoints`:  
 KV store endpoints (Default: ```127.0.0.1:2181```)
 
+`--providers.zookeeper.namespace`:  
+KV Namespace
+
 `--providers.zookeeper.password`:  
 KV Password