Update dev-quickstart doc

Do not use aufs to build images for Ubuntu systems

Change-Id: Ia14eaada3ec034a6ae340192dc69460df8885045

docs/dev-quickstart.md

@@ -51,6 +51,10 @@ Inc.:
 
     curl -sSL https://test.docker.com/ubuntu | sh
 
+For Ubuntu based systems, do not use aufs when starting Docker daemon. Instead
+use other storage options, e.g., btrfs. This is because cap_set_file is not
+permitted on aufs when building docker images.
+
 Next, install the OpenStack python clients if they are not installed:
 
     sudo yum install python-keystoneclient python-glanceclient \