docs: add brief description to portworx readme

Also hclfmt hcl snippet.

demo/csi/portworx-csi-plugin/README.md

@@ -1,3 +1,7 @@
+## Portworx CSI Plugin
+
+[Portworx](https://portworx.com/) is a software defined storage overlay which may be used via a CSI Plugin.
+
 ## Official documentation
 Before getting started, full documentation for using Portworx with Nomad can be found at [docs.portworx.com/install-with-other/nomad](https://docs.portworx.com/install-with-other/nomad).
 
@@ -13,14 +17,16 @@ The Portworx OCI-monitor container needs to run in privileged mode, so you need
 
 Add the following lines in your Nomad client configuration files and restart your clients:
 
-    plugin "docker" {
-        config {
-            allow_privileged = true
-            volumes {
-            enabled      = true
-            }
-        }
+```hcl
+plugin "docker" {
+  config {
+    allow_privileged = true
+    volumes {
+      enabled = true
     }
+  }
+}
+```
 
 ## Getting started
 
@@ -49,5 +55,3 @@ To start using the Portworx CSI Driver on Nomad, complete the follow steps:
 
 The open source control plane for Portworx can be found at the following repository:
 https://github.com/libopenstorage/openstorage/tree/master/csi
-
-