test sphinx plot generation by modifying plot_simple_path.py

[lobpcg]

#7025
#7040
#7042
raise the suspicion that sphinx plot generation is currently broken.
We test it by a trivial modification of a simple existing example.

[lobpcg]

Modification of plot_simple_path.py does produce the plot. Now testing the same plot in a new module.

[lobpcg]

The new module also produces the plot, so sphinx plot generation is working fine; and there is something wrong with my specific examples

• Create 3d_rotation_anime.py #7025
• Image (3D RGB data) segmentation by spectral clustering with 3D illustrations  #7040

[lobpcg]

@dschult my silly mistake - a module must be named plot_ to be processed for plotting in
#7025
#7040

[dschult]

Yay! I should have noticed that plot_ is needed... :}