anchor.diff:  The only similarities which can be used out of the box, without any further
   configuration are:
   
  -`classic`::
  -        The Default TF/IDF algorithm used by Elasticsearch and
  -        Lucene. See {defguide}/practical-scoring-function.html[Lucene’s Practical Scoring Function]
  +`BM25`::
  +        The Okapi BM25 algorithm. The algorithm used by default in Elasticsearch and Lucene.
  +        See {defguide}/pluggable-similarites.html[Pluggable Similarity Algorithms]
           for more information.
   
  -`BM25`::
  -        The Okapi BM25 algorithm.
  -        See {defguide}/pluggable-similarites.html[Pluggable Similarity Algorithms]
  +`classic`::
  +        The TF/IDF algorithm which used to be the default in Elasticsearch and
  +        Lucene. See {defguide}/practical-scoring-function.html[Lucene’s Practical Scoring Function]
           for more information.
   
   
  
positive.code: }
  --------------------------------------------------
  // CONSOLE
  <1> The `default_field` uses the `classic` similarity (ie TF/IDF).
  <2> The `bm25_field` uses the `BM25` similarity.
  
  
negative.code:         "default_field": { <1>
            "type": "text"
          },
          "classic_field": {
            "type": "text",
            "similarity": "classic" <2>
          }
        }
      }
  