message: Clarify comment about abstract names
diff: @@ -57,7 +57,7 @@ pub enum Name {
  /// [_ : t1] -> [_ : t2] -> t3
  /// ```
  ///
  - /// They should never actually appear in terms.
  + /// They should never actually appear as variables in terms.
  ///
  /// Comparing two abstract names will always return false because we cannot
  /// be sure what they actually refer to. For example, in the type
  