DOC: Updating API release note for colorbar interactivity

Author: greglucas

doc/api/next_api_changes/behavior/19515-GL.rst

@@ -3,4 +3,8 @@ Colorbars now have pan and zoom functionality
 
 Interactive plots with colorbars can now be zoomed and panned on
 the colorbar axis. This adjusts the *vmin* and *vmax* of the
-``ScalarMappable`` associated with the colorbar.
+``ScalarMappable`` associated with the colorbar. This is currently
+only enabled for continuous norms. Norms used with contourf and
+categoricals, such as ``BoundaryNorm`` and ``NoNorm``, have the
+interactive capability disabled by default. ``cb.ax.set_navigate()``
+can be used to set whether a colorbar axes is interactive or not.