Merge pull request #1177 from rootfs/azuredisk-doc

add azure disk volume doc

docs/user-guide/volumes.md

@@ -76,6 +76,7 @@ Kubernetes supports several types of Volumes:
    * `persistentVolumeClaim`
    * `downwardAPI`
    * `azureFileVolume`
+   * `azureDisk`
    * `vsphereVolume`
 
 We welcome additional contributions.
@@ -445,6 +446,12 @@ into a Pod.
 
 More details can be found [here](https://github.com/kubernetes/kubernetes/tree/{{page.githubbranch}}/examples/volumes/azure_file/README.md)
 
+### AzureDiskVolume
+
+A `AzureDiskVolume` is used to mount a Microsoft Azure [Data Disk](https://azure.microsoft.com/en-us/documentation/articles/virtual-machines-linux-about-disks-vhds/) into a Pod.
+
+More details can be found [here](https://github.com/kubernetes/kubernetes/tree/{{page.githubbranch}}/examples/volumes/azure_disk/README.md)
+
 ### vsphereVolume
 
 A `vsphereVolume` is used to mount a vSphere VMDK Volume into your Pod.  The contents