Backport of docs: clarify the behavior of prepending hostname to metrics into release/1.15.x (#17580)

* backport of commit 81fe71d411

* backport of commit 8d6b7070dd

---------

Co-authored-by: cskh <hui.kang@hashicorp.com>

website/content/docs/agent/config/config-files.mdx

@@ -1818,8 +1818,7 @@ subsystem that provides Consul's service mesh capabilities.
     geo location or datacenter, dc:sfo). By default, this is left blank and not used.
 
   - `disable_hostname` ((#telemetry-disable_hostname))
-    This controls whether or not to prepend runtime telemetry with the machine's
-    hostname, defaults to false.
+    Set to `true` to stop prepending the machine's hostname to gauge-type metrics. Default is `false`.
 
   - `dogstatsd_addr` ((#telemetry-dogstatsd_addr)) This provides the address
     of a DogStatsD instance in the format `host:port`. DogStatsD is a protocol-compatible

website/content/docs/agent/telemetry.mdx

@@ -27,6 +27,10 @@ This telemetry information can be used for debugging or otherwise
 getting a better view of what Consul is doing. Review the [Monitoring and
 Metrics tutorial](/consul/tutorials/day-2-operations/monitor-datacenter-health?utm_source=docs) to learn how collect and interpret Consul data.
 
+By default, all metric names of gauge type are prefixed with the hostname of the consul agent, e.g.,
+`consul.<hostname>.server.isLeader`. To disable prefixing the hostname, set
+`telemetry.disable_hostname=true` in the [agent configuration](/consul/docs/agent/config/config-files#telemetry).
+
 Additionally, if the [`telemetry` configuration options](/consul/docs/agent/config/config-files#telemetry)
 are provided, the telemetry information will be streamed to a
 [statsite](http://github.com/armon/statsite) or [statsd](http://github.com/etsy/statsd) server where