DOC fix kwargs parameter name in curvefit docstrings

doc/whats-new.rst

@@ -79,6 +79,11 @@ Documentation
 - Migrated from nbsphinx/jupyter-execute to myst-nb (:issue:`7924`, :pull:`11456`).
   By `Nick Hodgskin <https://github.com/VeckoTheGecko>`_.
 
+- Fixed the ``kwargs`` entry in the :py:meth:`Dataset.curvefit` and
+  :py:meth:`DataArray.curvefit` docstrings: both take a ``kwargs`` dict, not
+  ``**kwargs`` (:issue:`6891`).
+  By `Advit Arora <https://github.com/advitrocks9>`_.
+
 
 Internal Changes
 ~~~~~~~~~~~~~~~~

xarray/core/dataarray.py

@@ -6563,7 +6563,7 @@ def curvefit(
             If 'raise', any errors from the `scipy.optimize_curve_fit` optimization will
             raise an exception. If 'ignore', the coefficients and covariances for the
             coordinates where the fitting failed will be NaN.
-        **kwargs : optional
+        kwargs : optional
             Additional keyword arguments to passed to scipy curve_fit.
 
         Returns

xarray/core/dataset.py

@@ -9904,7 +9904,7 @@ def curvefit(
             If 'raise', any errors from the `scipy.optimize_curve_fit` optimization will
             raise an exception. If 'ignore', the coefficients and covariances for the
             coordinates where the fitting failed will be NaN.
-        **kwargs : optional
+        kwargs : optional
             Additional keyword arguments to passed to scipy curve_fit.
 
         Returns