DOC: cross ref the groupby tutorial (pydata#7555)

* DOC: cross ref the groupby tutorial

* DOC: cross ref the groupby tutorial

* DOC: change groupby ref description

* DOC: change groupby ref description

Author: jklymak

xarray/core/dataarray.py

@@ -6249,6 +6249,8 @@ def groupby(
 
         See Also
         --------
+        :ref:`groupby`
+            Users guide explanation of how to group and bin data.
         DataArray.groupby_bins
         Dataset.groupby
         core.groupby.DataArrayGroupBy
@@ -6328,6 +6330,8 @@ def groupby_bins(
 
         See Also
         --------
+        :ref:`groupby`
+            Users guide explanation of how to group and bin data.
         DataArray.groupby
         Dataset.groupby_bins
         core.groupby.DataArrayGroupBy

xarray/core/dataset.py

@@ -8933,6 +8933,8 @@ def groupby(
 
         See Also
         --------
+        :ref:`groupby`
+            Users guide explanation of how to group and bin data.
         Dataset.groupby_bins
         DataArray.groupby
         core.groupby.DatasetGroupBy
@@ -9014,6 +9016,8 @@ def groupby_bins(
 
         See Also
         --------
+        :ref:`groupby`
+            Users guide explanation of how to group and bin data.
         Dataset.groupby
         DataArray.groupby_bins
         core.groupby.DatasetGroupBy