Bug 23221: (follow-up) Add comments on markup structure

Bug 23221: (follow-up) Add comments on markup structure

This patch adds a few comments to the markup in order to highlight the
structure of the page.

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit 4068484650cb76d0fa3d801a4a5f49bd65cffb0b)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit 13eddb09b43d7b3939e37d4caacb111560b87c11)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>