move the calligra specific headers out of the way so dox generation
on api.kde.org follows the default styling there.

Calligra people: please create a project Mainpage.dox with some useful
content so the top-level dox looks nice and gives an overview.



R +0 -0 doc/api/calligra-header.html [from: doc/api/header.html - 100% similarity]
R +0 -0 doc/api/calligra-mainheader.html [from: doc/api/mainheader.html - 100% similarity]