Add removal note

dstansby · dstansby · commit 8bf6180d510e · 2020-07-26T13:27:45.000+01:00
diff --git a/doc/api/next_api_changes/removals/18073-DS.rst b/doc/api/next_api_changes/removals/18073-DS.rst
@@ -0,0 +1,5 @@
+``matplotlib.testing.disable_internet``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The entire ``matplotlib.testing.disable_internet`` sub-module has been removed.
+The `pytest-remotedata package <https://github.com/astropy/pytest-remotedata>`_
+can be used instead.
