website: add block_device attributes documentation in bsusurrogate

website/source/docs/builders/osc-bsusurrogate.html.md

@@ -125,6 +125,18 @@ builder.
     new OMI, the VM automatically launches with these additional volumes,
     and will restore them from snapshots taken from the source VM.
 
+      - `delete_on_vm_deletion` (boolean) - Indicates whether the BSU volume is deleted on VM termination. Default `false`. **NOTE**: If this value is not explicitly set to `true` and volumes are not cleaned up by an alternative method, additional volumes will accumulate after every build.
+
+      - `device_name` (string) - The device name exposed to the VM (for example, `/dev/sdh` or `xvdh`). Required for every device in the block device mapping.
+
+      - `iops` (number) - The number of I/O operations per second (IOPS) that the volume supports. See the documentation on
+        [IOPs](https://wiki.outscale.net/display/EN/About+Volumes#AboutVolumes-VolumeTypesVolumeTypesandIOPS)
+        for more information.
+
+      - `volume_size` (number) - The size of the volume, in GiB. Required if not specifying a `snapshot_id`
+
+      - `volume_type` (string) - The volume type. `gp2` for General Purpose (SSD) volumes, `io1` for Provisioned IOPS (SSD) volumes, and `standard` for Magnetic volumes
+
 - `run_tags` (object of key/value strings) - Tags to apply to the VM
     that is *launched* to create the OMI. These tags are *not* applied to the
     resulting OMIS unless they're duplicated in `tags`. This is a [template