message: Re-added comment to Score.
diff: @@ -245,6 +245,10 @@ pub type DocId = u32;
  /// with opstamp `n+1`.
  pub type Opstamp = u64;
  +/// A Score that represents the relevance of the document to the query
  +///
  +/// This is modelled internally as a `f32`. The larger the number, the more relevant
  +/// the document to the search query.
  pub type Score = f32;
  /// A `SegmentLocalId` identifies a segment.
  