MAINT: More explicit call while building docstrings.

Author: chebee7i

numpydoc/docscrape_sphinx.py

@@ -224,7 +224,7 @@ def __str__(self, indent=0, func_role="obj"):
         out += self._str_summary()
         out += self._str_extended_summary()
         out += self._str_param_list('Parameters')
-        out += self._str_returns()
+        out += self._str_returns('Returns')
         out += self._str_returns('Yields')
         for param_list in ('Other Parameters', 'Raises', 'Warns'):
             out += self._str_param_list(param_list)