Remove the usage of deprecated qdoc macros.

QDoc now has support for Doxygen style commands for italics, bold
and list items. This change applies that change in QDoc to the
actual documentation.

Task-number: QTBUG-24578
Change-Id: I519bf9c29b14092e3ab6067612f42bf749eeedf5
Reviewed-by: Shane Kearns <shane.kearns@accenture.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>