MNT: Update siphon home page link
MNT: Update siphon home page link

ahaberlie/MetPy,Unidata/MetPy,Unidata/MetPy,jrleeman/MetPy,dopplershift/MetPy,dopplershift/MetPy,ShawnMurd/MetPy,jrleeman/MetPy,ahaberlie/MetPy