image: add a NewUniform doc comment
image: add a NewUniform doc comment

Fixes #38739

Change-Id: I42b9b601e63ab8df69a0e5ce9bcabf75bb98d83e
Reviewed-on: https://go-review.googlesource.com/c/go/+/230777
Reviewed-by: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
Run-TryBot: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

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