clarify which parts of TM are experimental (elastic#101757)

Author: gmmorris

docs/user/production-considerations/task-manager-health-monitoring.asciidoc

@@ -6,6 +6,8 @@
 <titleabbrev>Health monitoring</titleabbrev>
 ++++
 
+experimental[]
+
 The Task Manager has an internal monitoring mechanism to keep track of a variety of metrics, which can be consumed with either the health monitoring API or the {kib} server log.
 
 The health monitoring API provides a reliable endpoint that can be monitored.

docs/user/production-considerations/task-manager-troubleshooting.asciidoc

@@ -60,6 +60,8 @@ For details on scaling Task Manager, see <<task-manager-scaling-guidance>>.
 [[task-manager-diagnosing-root-cause]]
 ==== Diagnose a root cause for drift
 
+experimental[]
+
 The following guide helps you identify a root cause for _drift_ by making sense of the output from the <<task-manager-health-monitoring>> endpoint.
 
 By analyzing the different sections of the output, you can evaluate different theories that explain the drift in a deployment.