Update simbad.rst
Update simbad.rst

While the previous query might have worked, the docs at http://simbad.u-strasbg.fr/simbad/sim-help?Page=sim-fscript clearly say "Epoch must be prefixed by 'B' or 'J'." Thus, I fixed the example to follow that rule.
ceb8/astroquery,ceb8/astroquery,imbasimba/astroquery,imbasimba/astroquery