Added documentation on getting full list of registered colormaps re: issue matplotlib#26244 (matplotlib#26930)

* closes matplotlib#26244, added documentation on getting full list of registered colormaps

Author: wemi3

galleries/users_explain/colors/colormaps.py

@@ -15,6 +15,11 @@
 help on creating your own colormaps, see
 :ref:`colormap-manipulation`.
 
+To get a list of all registered colormaps, you can do::
+
+    from matplotlib import colormaps
+    list(colormaps)
+
 Overview
 ========
 

lib/matplotlib/cm.py

@@ -74,6 +74,11 @@ class ColormapRegistry(Mapping):
     Additional colormaps can be added via `.ColormapRegistry.register`::
 
         mpl.colormaps.register(my_colormap)
+
+    To get a list of all registered colormaps, you can do::
+
+        from matplotlib import colormaps
+        list(colormaps)
     """
     def __init__(self, cmaps):
         self._cmaps = cmaps