Add removal note

dstansby · dstansby · commit c6d32af28e8f · 2020-07-26T13:11:53.000+01:00
diff --git a/doc/api/next_api_changes/removals/18071-DS.rst b/doc/api/next_api_changes/removals/18071-DS.rst
@@ -0,0 +1,9 @@
+`matplotlib.animation`
+~~~~~~~~~~~~~~~~~~~~~~
+
+The following `~.animation.MovieWriterRegistry` methods have been removed:
+
+- ``.set_dirty()`` - does nothing.
+- ``.esnure_not_dirty()`` - does nothing.
+- ``.reset_available_writers()`` - does nothing.
+- ``.avail()`` - use ``.list()`` instead to get a list of available writers.
