Merge pull request #24109 from jklymak/doc-add-API-note-colorbar-issue

DOC: add API change note for colorbar deprecation

doc/api/next_api_changes/deprecations/24088-JMK.rst

@@ -0,0 +1,9 @@
+Colorbars for orphaned mappables are deprecated, but no longer raise
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Before 3.6.0, Colorbars for mappables that do not have a parent axes would
+steal space from the current Axes.  3.6.0 raised an error on this, but without
+a deprecation cycle.  For 3.6.1 this is reverted, the current axes is used,
+but a deprecation warning is shown instead.  In this undetermined case users
+and libraries should explicitly specify what axes they want space to be stolen
+from: ``fig.colorbar(mappable, ax=plt.gca())``.