Description

The first and second image of the doc of Variable Bayesian Gaussian Mixture are the same. This is due to a simple typo in the file name.

While fixing this, as per @tguillemot 's advice, it might be beneficial to modify plot_concentration_prior.py too, since the default value of the align parameter of ax.bar() has changed from edge to center in matplotlib 2.0 (changelog), so the bar charts are off when the script is run with matplotlib 2.

I am sending a PR.