authentication vs documentation

authentication

noun
  • something which validates or confirms the authenticity of something 

  • proof of the identity of a user logging on to some network 

  • a hallmark or assay-mark on a piece of metalwork 

documentation

noun
  • Documents that explain the operation of a particular machine or software program. 

  • Documentary evidence and sources. 

  • Something transposed from a thought to a document; the written account of an idea. 

  • Comments that explain the usage of individual functions, libraries and blocks of code. 

  • A documentary. 

How often have the words authentication and documentation occurred in a corpus of books? (source: Google Ngram Viewer )