Fix typo in header (kubernetes#1075)

Author: mikejoh

docs/using-cinder-csi-plugin.md

@@ -43,7 +43,7 @@ To install the chart use the following command:
 helm install --namespace kube-system --name cinder-csi ./charts/cinder-csi-plugin
 ```
 
-#### Using the maninfests
+#### Using the manifests
 
 If you already created the `cloud-config` secret used by the [cloud-controller-manager](https://github.com/kubernetes/cloud-provider-openstack/blob/master/docs/using-openstack-cloud-controller-manager.md#steps), remove the file ```manifests/cinder-csi-plugin/csi-secret-cinderplugin.yaml``` from [manifests](https://github.com/kubernetes/cloud-provider-openstack/tree/master/manifests/cinder-csi-plugin) and then jump directly to the `kubectl apply ...` command.