Fix Portworx name in doc

Signed-off-by: Dinesh Israni <disrani@portworx.com>

docs/support-matrix.md

@@ -28,7 +28,7 @@ _Note that these providers are not regularly tested by the Ark team._
 | [Azure Managed Disks][3]         | Ark Team        | [Slack][10], [GitHub Issue][11] |
 | [Google Compute Engine Disks][4] | Ark Team        | [Slack][10], [GitHub Issue][11] |
 | [Restic][1]                      | Ark Team        | [Slack][10], [GitHub Issue][11] |
-| [Portworx][6]                    | PortWorx        |                                 |
+| [Portworx][6]                    | Portworx        |                                 |
 | [DigitalOcean][7]                | StackPointCloud |                                 |
 
 ### Adding a new plugin
@@ -48,4 +48,4 @@ After you publish your plugin, open a PR that adds your plugin to the appropriat
 [9]: quickstart.md
 [10]: https://kubernetes.slack.com/messages/ark-dr
 [11]: https://github.com/heptio/ark/issues
-[12]: https://github.com/aws/aws-sdk-go/aws
+[12]: https://github.com/aws/aws-sdk-go/aws