Plot GO DAGs for all sections (not Misc.).

def plot_sections(self, fout_dir=".", **kws_pltargs):
        """Plot GO DAGs for all sections (not Misc.)."""
        hdrgos = self.grprobj.hdrobj.get_section_hdrgos()
        pltargs = PltGroupedGosArgs(self.grprobj, fout_dir=fout_dir, **kws_pltargs)
        return self._plot_groups_hdrgos(hdrgos, pltargs)