add a little space above h2->h6 - it gets a bit dense in there when there are lots of steps

@dhrp - I'm also wondering if we can reduce the size of the h2's - when we use them for each step of an example, things get very heavy fast..

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au> (github: SvenDowideit)