Fix method name in docstring.

Author: mkelley

astroquery/mpc/core.py

@@ -779,7 +779,7 @@ def get_observations_async(self, targetid, *,
 
         .. deprecated:: 0.4.9
            The ``get_raw_response`` keyword argument is deprecated.  The
-           `~MPCClass.get_observationsephemerides_async` method will return a raw response.
+           `~MPCClass.get_observations_async` method will return a raw response.
 
 
         Parameters