Wrong visualization of doublets cluster

[VladimirShitov]

Describe the bug

There is a not critical error in the visualization on this page: https://www.sc-best-practices.org/preprocessing_visualization/quality_control.html

The cluster of doublets is located separately from the singlet clusters. For UMAP/TSNE it would be correct, but in PCA space, it would necessarily be located in between of these clusters.

So, to easily make it correct, you can put UMAP on the axes labels. A bit more difficult fix would require changing the location of clusters