Update volumes.md

Update docs and example for NFS Plugin

Modified the wording around how many Volumes exist

Cleaned up the text around the NFS Pod description

Fixed Spelling mistake on read-only

examples/nfs/test.yaml

@@ -6,12 +6,12 @@ desiredState:
         image: dockerfile/nginx
         volumeMounts:
             # name must match the volume name below
-            - name: nfs
+            - name: myshare
               mountPath: "/var/www/html/mount-test"
     id: nfspd
     version: v1beta1
     volumes:
-      - name: nfs
+      - name: myshare
         source:
           nfs:
             server: "172.17.0.2"