Make titles more consistent

This patch aims to bring config reference titles more consistents
to let the user understand the structure at a first glance.

backport: havana

Change-Id: I163e508621c7a46c753836a4743b32af25acf011
Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>
Merge "Make titles more consistent"