Add intersphinx mapping to other docs.
Add intersphinx mapping to other docs.

ahill818/MetPy,Unidata/MetPy,ahaberlie/MetPy,dopplershift/MetPy,deeplycloudy/MetPy,dopplershift/MetPy,ShawnMurd/MetPy,Unidata/MetPy,jrleeman/MetPy,jrleeman/MetPy,ahaberlie/MetPy