Bug 31932: (follow-up) Markup comments

Bug 31932: (follow-up) Markup comments

This patch adds comments to the template to highlight the markup
structure.

This patch should have no effect on the page's appearance or
functionality.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit bbec1228b62c81c0fa9e4a330cd4b28aed27ca99)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>