Remove redundant axes_grid colorbar examples.

simple_colorbar is basically a shorter version of
demo_colorbar_with_axes_divider with no text explanation (and a really
confusing title -- we don't actually want most users to even look at
that example), so just delete it (with a redirection).

demo_colorbar_with_inset_axes is a version of
demo_colorbar_with_inset_locator, but specialized for adding a colorbar
to an inset axes.  That's a rather specialized case and anyways it works
"as is" without doing anything special -- it's just saying that you can
combine two relatively orthogonal features and they are happy together.
So just delete it (with a redirection).

Author: anntzer

galleries/examples/axes_grid1/demo_colorbar_of_inset_axes.py

@@ -14,6 +14,8 @@
 Users should consider simply passing the main axes to the *ax* keyword argument of
 `~.Figure.colorbar` instead of creating a locatable axes manually like this.
 See :ref:`colorbar_placement`.
+
+.. redirect-from:: /gallery/axes_grid1/simple_colorbar
 """
 
 import matplotlib.pyplot as plt

galleries/examples/axes_grid1/demo_colorbar_with_axes_divider.py

@@ -16,6 +16,7 @@
 Users should consider using `.Axes.inset_axes` instead (see
 :ref:`colorbar_placement`).
 
+.. redirect-from:: /gallery/axes_grid1/demo_colorbar_of_inset_axes
 """
 
 import matplotlib.pyplot as plt

galleries/examples/axes_grid1/demo_colorbar_with_inset_locator.py

@@ -81,8 +81,8 @@ side ("left", "right", "top", "bottom") of the original axes.
 colorbar whose height (or width) is in sync with the main axes
 --------------------------------------------------------------
 
-.. figure:: /gallery/axes_grid1/images/sphx_glr_simple_colorbar_001.png
-   :target: /gallery/axes_grid1/simple_colorbar.html
+.. figure:: /gallery/axes_grid1/images/sphx_glr_demo_colorbar_with_axes_divider_001.png
+   :target: /gallery/axes_grid1/demo_colorbar_with_axes_divider.html
    :align: center
 
 scatter_hist.py with AxesDivider