design/go2draft-contracts: mark as superseded

Change-Id: If7c663992ceb503af12f3f8d41213908373fdab5
Reviewed-by: Robert Griesemer <>
diff --git a/design/ b/design/
index d4dbb0e..07760c2 100644
--- a/design/
+++ b/design/
@@ -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+## Superseded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+It has been replaced by a [new design
+This document exists for historical context.
 ## Abstract
 We suggest extending the Go language to add optional type parameters