text: Title: Improve description in Step 2 for the example
  Body: The description in Step 2 does not seem very clear, e.g., in " internal node is a parent of that internal node", it is not clear which nodes are referred to here. It would be good to walk through how one column of C is constructed. Should the second column be (1,-1,0,1)? It would be nice to have some more intuition about C and D. 
  
  There is also a typo: "tenor".