doc: refer to SHAKE in #69518 release note

Change-Id: I6a6a46560b5d78710bd09d2452c80e51da936ec7
Reviewed-on: https://go-review.googlesource.com/c/go/+/675196
Auto-Submit: Filippo Valsorda <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Roland Shoemaker <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: FiloSottile

doc/next/6-stdlib/99-minor/hash/69518.md

@@ -1,3 +1,3 @@
 The new [XOF](/pkg/hash#XOF) interface can be implemented by "extendable output
 functions", which are hash functions with arbitrary or unlimited output length
-such as [BLAKE2Xb](https://pkg.go.dev/golang.org/x/crypto/blake2b).
+such as [SHAKE](https://pkg.go.dev/crypto/sha3#SHAKE).