Update vsphere+vsphere-template array pairing docs

The example and description of pairing `vsphere` and `vsphere-template` in a JSON array is accurate but ought to be more spelled out.
This introduces a change which makes that part of the example and docs more verbose, hopefully mitigating potential confusion.

website/source/docs/post-processors/vsphere-template.html.md

@@ -91,7 +91,11 @@ for more information):
         "type": "vsphere-template",
          ...
       }
-    ]
+    ],
+    {
+      "type": "...",
+      ...
+    }
   ]
 }
 ```
@@ -100,4 +104,5 @@ In the example above, the result of each builder is passed through the defined
 sequence of post-processors starting with the `vsphere` post-processor which
 will upload the artifact to a vSphere endpoint. The resulting artifact is then
 passed on to the `vsphere-template` post-processor which handles marking a VM
-as a template.
+as a template. Note that the `vsphere` and `vsphere-template` post-processors
+are paired together in their own JSON array.