Use shorter links

Author: bsipocz

astroquery/astrometry_net/core.py

@@ -219,7 +219,7 @@ def monitor_submission(self, submission_id, *,
         Returns
         -------
 
-        None or `astropy.io.fits.Header` or (`astropy.io.fits.Header`, str)
+        None or `~astropy.io.fits.Header` or (`~astropy.io.fits.Header`, str)
             The contents of the returned object depend on whether the solve
             succeeds or fails. If the solve succeeds the header with
             the WCS solution generated by astrometry.net is returned. A tuple