Remove unnecessary Linode-specific instructions

Modern versions of Docker work just fine on Linode's default kernel
thanks to the `overlay2` storage driver.

Closes #2675

bootstrap.sh

@@ -117,12 +117,6 @@ install-dokku-from-deb-package() {
   apt-get -qq -y install apt-transport-https
 
   echo "--> Installing docker"
-  if uname -r | grep -q linode; then
-    echo "--> NOTE: Using Linode? Docker might complain about missing AUFS support."
-    echo "    See http://dokku.viewdocs.io/dokku/getting-started/install/linode/"
-    echo "    Installation will continue in 10 seconds."
-    sleep 10
-  fi
   wget -nv -O - https://get.docker.com/ | sh
 
   echo "--> Installing dokku"