[DOCS] Add monitoring upgrade details
@@ -16,7 +16,14 @@ To upgrade using a zip or compressed tarball:
.. Set `path.data` in `config/elasticsearch.yml` to point to your external
data directory. If you are not using an external `data` directory, copy
- your old data directory over to the new installation.
+ your old data directory over to the new installation. +
++
+--
+IMPORTANT: If you use {monitoring}, re-use the data directory when you upgrade
+{es}. Monitoring identifies unique {es} nodes by using the persistent UUID, which
+is stored in the data directory.
+
+--
.. Set `path.logs` in `config/elasticsearch.yml` to point to the location
where you want to store your logs. If you do not specify this setting,
