CORD-2718: Change Quagga version on cord 4.1 branch

Change-Id: I80379d96f77d5f8671ef0441e2492ab13c78eb41
diff --git a/docs/vrouter.md b/docs/vrouter.md
index 9c2e3b6..02dc577 100644
--- a/docs/vrouter.md
+++ b/docs/vrouter.md
@@ -185,10 +185,11 @@
 ### Download the image and pipework
 
 CORD uses a slightly modified version of Quagga, so the easiest way to deploy
-this is to use the provided docker image.
+this is to use the provided docker image. In CORD 4.x we use ONOS 1.10.x, so
+we will pull a version of Quagga that maches the ONOS version.
 
 ```
-docker pull opencord/quagga
+docker pull opencord/quagga:onos-1.10
 ```
 
 We also need to download the `pipework` tool which will be used to connect the