add warning about hostPath volumes (#47129)

* add warning about hostPath volumes

* Update content/en/docs/concepts/storage/volumes.md

Co-authored-by: Qiming Teng <[email protected]>

---------

Co-authored-by: Qiming Teng <[email protected]>

Author: pegasas

content/en/docs/concepts/storage/volumes.md

@@ -397,6 +397,9 @@ or as read-write, because:
   parts of the cluster.
 * Pods with identical configuration (such as created from a PodTemplate) may
   behave differently on different nodes due to different files on the nodes.
+* `hostPath` volume usage is not treated as ephemeral storage usage.
+  You need to monitor the disk usage by yourself because excessive `hostPath` disk
+  usage will lead to disk pressure on the node.
 {{< /warning >}}
 
 Some uses for a `hostPath` are: