_content/doc/go1.18: move sha1 removal to unspecified future release
_content/doc/go1.18: move sha1 removal to unspecified future release

Change-Id: I747e2c8b42bb4ccc90979adb4fbfe76441fec389
Reviewed-on: https://go-review.googlesource.com/c/website/+/396754
Trust: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>
Reviewed-by: Filippo Valsorda <5116fe0442846a38fe5f19d63723d023eca87d1d@google.com>

golang/website,golang/website,golang/website,golang/website,golang/website,golang/website,golang/website