message: Document prom-client path fix
diff: @@ -5,6 +5,7 @@ Any changes, including backwards incompatible changes will be listed here
  ## HEAD
  - Deprecated PMX configuration option. Use prom-client for monitoring
  +- Fix: Prom client uses stricter path matching to reduce cardinaility in `path=` label
  ## 10.1.3 (23/3/2019)
  