[chore] Update 3.0 Config.md file (#4148)

update 3.0

src/gateway/reference/configuration.md

@@ -7,6 +7,7 @@
 title: Configuration Reference for Kong Gateway
 source_url: https://github.com/Kong/kong-ee/blob/master/kong.conf.default
 ---
+<!-- vale off -->
 
 ## Configuration loading
 
@@ -743,6 +744,14 @@ node to which telemetry updates will be posted in `host:port` format.
 
 **Default:** none
 
+---
+#### cluster_telemetry_server_name
+{:.badge .enterprise}
+
+The SNI (Server Name Indication extension) to use for Vitals telemetry data.
+
+**Default:** none
+
 ---
 
 #### data_plane_config_cache_mode