Axes.plot: remove set_default_color_cycle from the docstring

It has been removed in 2c24a7c.

Author: mineo

lib/matplotlib/axes/_axes.py

@@ -1224,8 +1224,7 @@ def plot(self, *args, **kwargs):
 
         By default, each line is assigned a different color specified by a
         'color cycle'.  To change this behavior, you can edit the
-        axes.color_cycle rcParam. Alternatively, you can use
-        :meth:`~matplotlib.axes.Axes.set_default_color_cycle`.
+        axes.color_cycle rcParam.
 
         The following format string characters are accepted to control
         the line style or marker: