message: Fix typo in Descriptor doc
diff: @@ -89,8 +89,8 @@ public:
  /// returns `not_found`.
  size_t get_column_index(StringData name) const noexcept;
  - /// Get the index of the column to which links in the column at the
  - /// specified index refer.
  + /// Get the index of the table to which links in the column at the specified
  + /// index refer.
  ///
  /// The consequences of specifying a column index that is out of
  /// range, are undefined.
  