KDE exports QT_PLUGIN_PATH which prevents calculatorbuilder example to launch

It should be mentioned in Qt installation documentation that the QT_PLUGIN_PATH should point to correct location.
KDE sets QT_PLUGIN_PATH to point to the Qt plugins shipped with KDE which prevents correct plugins from loading for calculatorbuilder example.

KDE QT_PLUGIN_PATH:
QT_PLUGIN_PATH=/home/user/.kde/lib64/kde4/plugins/:/usr/lib64/kde4/plugins/

That should be replaced with something like:
QT_PLUGIN_PATH=$QT_INSTALL_PATH/plugins