Remove outdated comment
Remove outdated comment

Previously I was setting `-s overlay` in /etc/default/docker and had to
convince apt not to complain that file differed from the maintainer version.
Not doing that any more.

Signed-off-by: Ken Simon <d689d7adec1f250ae6789ab10f904ed792f264cd@gmail.com>

heptio/aws-quickstart,heptio/aws-quickstart,captainshar/aws-quickstart