[skip-ci] fix links

Author: dcherian

doc/conf.py

@@ -147,14 +147,18 @@
     "matplotlib colormap name": ":doc:`matplotlib colormap name <matplotlib:gallery/color/colormap_reference>`",
     "matplotlib axes object": ":py:class:`matplotlib axes object <matplotlib.axes.Axes>`",
     "colormap": ":py:class:`colormap <matplotlib.colors.Colormap>`",
-    # objects without namespace
+    # objects without namespace: xarray
     "DataArray": "~xarray.DataArray",
     "Dataset": "~xarray.Dataset",
     "Variable": "~xarray.Variable",
+    "DatasetGroupBy": "~xarray.core.weighted.DatasetGroupBy",
+    "DataArrayGroupBy": "~xarray.core.weighted.DataArrayGroupBy",
+    # objects without namespace: numpy
     "ndarray": "~numpy.ndarray",
     "MaskedArray": "~numpy.ma.MaskedArray",
     "dtype": "~numpy.dtype",
     "ComplexWarning": "~numpy.ComplexWarning",
+    # objects without namespace: pandas
     "Index": "~pandas.Index",
     "MultiIndex": "~pandas.MultiIndex",
     "CategoricalIndex": "~pandas.CategoricalIndex",