Avoid short pages in kate configuring docbook

fix wrong link to the link Editor Component Configuration section of the KatePart Handbook
move page https://docs.kde.org/trunk5/en/applications/kate/config-dialog-editor.html
and https://docs.kde.org/trunk5/en/applications/kate/config-variables.html
both only one sentence to the end of the page
https://docs.kde.org/trunk5/en/applications/kate/config-dialog.html

Differential Revision: https://phabricator.kde.org/D13094