doc/go1.19: add pdqsort change to release notes
doc/go1.19: add pdqsort change to release notes

Change-Id: I4a36491e561f3b2112f980ff580fa4f85d501b6a
Reviewed-on: https://go-review.googlesource.com/c/go/+/408834
Auto-Submit: Eli Bendersky‎ <e83e4a9813852caf164372e4b6bd506b7819d6ab@golang.org>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Run-TryBot: Eli Bendersky‎ <e83e4a9813852caf164372e4b6bd506b7819d6ab@golang.org>
Reviewed-by: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@google.com>
Reviewed-by: Eli Bendersky <e83e4a9813852caf164372e4b6bd506b7819d6ab@google.com>

golang/go,nawawi/go,nawawi/go,nawawi/go,nawawi/go,golang/go,golang/go,nawawi/go,nawawi/go,golang/go,golang/go,golang/go,golang/go,golang/go,nawawi/go,nawawi/go