[v14] Update docs to call out acme is not for HA (#40482)

* Update docs to call out acme is not for HA

based on user issues, until #27613 (comment) is implemented we should call out that using ACME is not for HA deployments

* Update proxy-service.yaml

docs/pages/includes/config-reference/proxy-service.yaml

@@ -127,6 +127,9 @@ proxy_service:
     # Also set using the CLI command:
     # 'teleport configure --acme [email protected] \
     # --cluster-name=tele.example.com -o file'
+    # This should NOT be enabled in a highly available Teleport deployment
+    # Using in HA can lead to too many failed authorizations and a lock-up
+    # of the ACME process (https://letsencrypt.org/docs/failed-validation-limit/)
     #acme:
     #  enabled: yes
     #  email: [email protected]