text: Title: Purpose of Procrustes Analysis
  Body: Hi there,
  
  I am using PHATE on data sets with much success, and I am looking to understand the purpose of the procrustes analysis between the classical MDS embedding and the metric MDS embedding in the embed_mds function. This is not necessarily an issue, but I couldn't find any documentation in the paper "Visualizing structure and transitions in high-dimensional biological data" on the matter. 
  
  Thank you!
  Josh