D28041: Use range constructor to compile with Qt 5.14

[Albert Astals Cid]

aacid added a reviewer: mlaurent.

REPOSITORY
  R125 KHelpCenter

REVISION DETAIL
  https://phabricator.kde.org/D28041

To: yurchor, #kde_applications, mlaurent
Cc: kde-doc-english, gennad, fbampaloukas, skadinna