DOC remove boston from tutorial.rst (scikit-learn#16889)

doc/tutorial/basic/tutorial.rst

@@ -77,8 +77,8 @@ Loading an example dataset
 `scikit-learn` comes with a few standard datasets, for instance the
 `iris <https://en.wikipedia.org/wiki/Iris_flower_data_set>`_ and `digits
 <https://archive.ics.uci.edu/ml/datasets/Pen-Based+Recognition+of+Handwritten+Digits>`_
-datasets for classification and the `boston house prices dataset
-<https://archive.ics.uci.edu/ml/machine-learning-databases/housing/>`_ for regression.
+datasets for classification and the `diabetes dataset
+<https://www4.stat.ncsu.edu/~boos/var.select/diabetes.html>`_ for regression.
 
 In the following, we start a Python interpreter from our shell and then
 load the ``iris`` and ``digits`` datasets.  Our notational convention is that