i've made a 2nd slackbuild to create a doc-only package (which needs to be built only on version bump, not bugfixes)
Code:
export CFLAGS="$SLKCFLAGS"
export CXXFLAGS="$SLKCFLAGS"
export OPENSOURCE_CXXFLAGS="$SLKCFLAGS"
./configure -confirm-license -opensource -prefix /usr/lib64/qt -fast -system-libpng -system-libjpeg -system-zlib -system-sqlite -plugin-sql-sqlite -dbus -webkit -no-phonon -nomake examples -nomake demos -no-separate-debug-info -no-pch || exit 1
make install_htmldocs INSTALL_ROOT=$PKG || exit 1
make install_qchdocs INSTALL_ROOT=$PKG || exit 1
make install_docimages INSTALL_ROOT=$PKG || exit 1
make install_examplesmanifest INSTALL_ROOT=$PKG || exit 1
make install_demosmanifest INSTALL_ROOT=$PKG || exit 1
abobe and below it's as the same as main qt slackbuild