design/43651-type-parameters: use ~ in SliceConstraint

Change-Id: Ifb4c3bcdc382d64b469616f311399af6fbe180f1
Reviewed-on: https://go-review.googlesource.com/c/proposal/+/366014
Trust: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/design/43651-type-parameters.md b/design/43651-type-parameters.md
index 64f29ea..454059e 100644
--- a/design/43651-type-parameters.md
+++ b/design/43651-type-parameters.md
@@ -2074,7 +2074,7 @@
 // SliceConstraint is a type constraint that matches a slice of
 // the type parameter.
 type SliceConstraint[T any] interface {
-	[]T
+	~[]T
 }
 
 // Map takes a slice of some element type and a transformation function,