message: Improve unification documentation
diff: @@ -27,10 +27,9 @@ pub enum ProblemSource {
  /// Elaboration diagnostic messages.
  #[derive(Debug, Clone)]
  pub enum Message {
  - UnboundName {
  - range: ByteRange,
  - name: StringId,
  - },
  + /// The name was not previously bound in the current scope.
  + UnboundName { range: ByteRange, name: StringId },
  + /// Unification errors.
  FailedToUnify {
  range: ByteRange,
  // TODO: add lhs and rhs values
  @@ -38,10 +37,12 @@ pub enum Message {
  // rhs: Doc<_>,
  error: unification::Error,
  },
  + /// A unification problem was not yet solved.
  UnsolvedProblem {
  range: ByteRange,
  source: ProblemSource,
  },
  + /// An error occurred during evaluation, and is almost certainly a bug.
  Semantics(semantics::Error),
  }
  