doc/go1.12: add more release notes for various packages
doc/go1.12: add more release notes for various packages

Change-Id: Ie11cf7d8204860f5a61ab650589d44072d6b131c
Reviewed-on: https://go-review.googlesource.com/c/152740
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

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