design/go2draft-contracts: mark as superseded
Change-Id: If7c663992ceb503af12f3f8d41213908373fdab5
Reviewed-on: https://go-review.googlesource.com/c/proposal/+/238004
Reviewed-by: Robert Griesemer <gri@golang.org>
diff --git a/design/go2draft-contracts.md b/design/go2draft-contracts.md
index d4dbb0e..07760c2 100644
--- a/design/go2draft-contracts.md
+++ b/design/go2draft-contracts.md
@@ -4,6 +4,13 @@
Robert Griesemer\
July 31, 2019
+## Superseded
+
+We will not be pursuing the approach outlined in this design draft.
+It has been replaced by a [new design
+draft](https://go.googlesource.com/proposal/+/refs/heads/master/design/go2draft-type-parameters.md).
+This document exists for historical context.
+
## Abstract
We suggest extending the Go language to add optional type parameters
