doc/go1.19: delete boringcrypto TODO
doc/go1.19: delete boringcrypto TODO

Boringcrypto has never been officially supported and it remains unsupported.
It need not be mentioned in the release notes.

Change-Id: I24a08d424982615244d51c1d250035d85a602023
Reviewed-on: https://go-review.googlesource.com/c/go/+/410362
Run-TryBot: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>
Reviewed-by: Carlos Amedee <ab5e2bca84933118bbc9d48ffaccce3bac4eeb64@golang.org>
Reviewed-by: Heschi Kreinick <e89ab2b172855aa0ad01c40c4d8a3535a61ac68a@google.com>

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