doc/go1.15: encoding/json's CL 191783 was reverted
See golang.org/cl/240657, which reverted the original change to fix the
regression reported in golang.org/issue/39427.
Updates #37419.
Change-Id: I39fbaa0b028ee00856cffea38879a631f540f057
Reviewed-on: https://go-review.googlesource.com/c/go/+/247718
Reviewed-by: Andrew Bonventre <andybons@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Andrew Bonventre <andybons@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>