doc: document new default for GODEBUG gotypesalias setting in release notes

For #65614.

Change-Id: I9487521817348053170da293c01ac55f6e3dcd20
Reviewed-on: https://go-review.googlesource.com/c/go/+/590895
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Robert Griesemer <[email protected]>
Auto-Submit: Robert Griesemer <[email protected]>
TryBot-Bypass: Robert Griesemer <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>

Author: griesemer

doc/next/6-stdlib/99-minor/go/types/cl-577715.md

@@ -0,0 +1,4 @@
+<!-- CL 577715, CL 579076 -->
+By default, go/types now produces [Alias] type nodes for type aliases.
+This behavior can be controlled by the `GODEBUG` `gotypesalias` flag.
+Its default has changed from 0 in Go 1.22 to 1 in Go 1.23.