Package check result: NOTE

Check: CRAN incoming feasibility, Result: NOTE
  Maintainer: ‘Michael Hahsler <mhahsler@lyle.smu.edu>’
  
  Found the following (possibly) invalid URLs:
    URL: https://www.amazon.com/Building-Recommendation-System-Suresh-Gorakala/dp/1783554495
      From: README.md
      Status: 500
      Message: Internal Server Error

No changes to worse in reverse depends.