Remove VM storage concept document

Author: pjw711

articles/operator-nexus/TOC.yml

@@ -20,8 +20,6 @@
           href: concepts-storage-multiple-appliances.md
         - name: Storage for Nexus Kubernetes
           href: concepts-storage-kubernetes.md
-        - name: Storage for Nexus Virtual Machines
-          href: concepts-storage-virtual-machine.md
     - name: Cluster deployment and upgrades
       expanded: false
       items: