D11592: Update kate docbooks to 18.04

[Burkhard Lück]

lueck marked 3 inline comments as done.

REVISION DETAIL
  https://phabricator.kde.org/D11592

To: lueck, #kate, kossebau, #documentation, yurchor
Cc: yurchor, kde-doc-english, michaelh, kevinapavew, ngraham, demsking, 
cullmann, sars, dhaumann