doc: remove CL 159258 from 1.13 release notes list
doc: remove CL 159258 from 1.13 release notes list

It was rolled back.

Change-Id: I8372bb7e11bab7be242f4af7093a73d2fa093067
Reviewed-on: https://go-review.googlesource.com/c/go/+/180760
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

akutz/go,CAFxX/go,nawawi/go,nawawi/go,cloudflare/go,cloudflare/go,CAFxX/go,nawawi/go,cloudflare/go,nawawi/go,akutz/go,cloudflare/go,CAFxX/go,golang/go,cloudflare/go,akutz/go,akutz/go,cloudflare/go,golang/go,nawawi/go,CAFxX/go,CAFxX/go,golang/go,akutz/go,CAFxX/go,cloudflare/go,akutz/go,golang/go,golang/go,golang/go,CAFxX/go,cloudflare/go,akutz/go,CAFxX/go,nawawi/go,nawawi/go,golang/go,golang/go,nawawi/go,akutz/go