message: docs: healthcheck clarification
  Clarify that health checks will happen over TLS if the cluster is configured to use TLS. I think this is worth clarifying since there are no TLS-related configurations on the health checks.
diff: @@ -26,6 +26,9 @@ unhealthy, successes required before marking a host healthy, etc.):
  maintenance by setting the specified key to any value and waiting for traffic to drain. See
  :ref:`redis_key <envoy_api_msg_config.health_checker.redis.v2.Redis>`.
  +Health checks occur over the transport socket specified for the cluster. This implies that if a cluster is
  +using a TLS-enabled transport socket, the health check will also occur over TLS.
  +
  .. _arch_overview_per_cluster_health_check_config:
  Per cluster member health check config
  