Updated core

Project: help  3b48a6feb0728a07fba8213ee39f39bb835812f3

Improve EPUB help page

After some remarks from translators.
Added localized dialog too.
Added Adolfo suggestions.

Change-Id: Ie7311bb6f612284baa69a26c929cda99fda4e0a9
Reviewed-on: https://gerrit.libreoffice.org/53630Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>

helpcontent2 @ 3b48a6fe

-Subproject commit 4fa9fb343ca0d2fd3e0481c8e12e9661c96c9430
+Subproject commit 3b48a6feb0728a07fba8213ee39f39bb835812f3