Extending makefile to pdf and html output

I want to add the production of pdf and html.  How would one
change this makefile?

btnver =3D hist-1.0
prxdir =3D ${HOME}/Opfeld/hist/1-devel
srcdir =3D ${prxdir}/${btnver}/orellana/skemaru/antares

trgdir =3D ${HOME}/Opfeld/hist/installs/${btnver}

MAKEINFO =3D makeinfo
MAKEINFOFLAGS =3D --no-split

.PHONY: info

info: $(trgdir)/antares.info

$(trgdir)/%.info: $(srcdir)/%.texi
=09## Make any missing parent directories
=09mkdir -p $(trgdir)
=09$(MAKEINFO) $(MAKEINFOFLAGS) -o $@ $<

clean:
=09rm -f ${trgdir}/antares.info