Update storage-persistent-storage-pv.adoc

Here is the documentation link:
https://docs.redhat.com/en/documentation/openshift_container_platform/4.14/html/storage/understanding-persistent-storage#pv-phase_understanding-persistent-storage

Here is the current look of the command:
$ oc get pv <pv-claim>
In the above command, <pv-claim> is mentioned with `hyphens`.
But as per the standard rule, it needs to be mentioned with an `underscore`.
Hence, it should be changed to `<pv_claim> `.
Here is the updated look of the command:
$ oc get pv <pv_claim>

Author: prithvipatil97

modules/storage-persistent-storage-pv.adoc

@@ -255,7 +255,7 @@ You can view the name of the PVC that is bound to the PV by running the followin
 
 [source,terminal]
 ----
-$ oc get pv <pv-claim>
+$ oc get pv <pv_claim>
 ----
 
 [id="pv-mount-options_{context}"]
@@ -342,4 +342,4 @@ allowVolumeExpansion: true
 ====
 `mountOptions` are not validated. Incorrect values will cause the mount to fail and an event to be logged to the PVC.
 ====
-endif::microshift[]
+endif::microshift[]