Add link to Bayestar2019

A simple url can be added with (lon, lat) data to see the Bayestar data for that cluster , Replace `XXGLONXX, XXGLATXX`with the actual values in the url below

http://argonaut.skymaps.info/query?lon=XXGLONXX%20&lat=XXGLATXX&coordsys=gal&mapname=bayestar2019