backport (v1.13): docs: Promote Deny Policies out of Beta

[nathanjsweet]

No description provided.

[michi-covalent]

probably missing some context, but do we usually change the status of a feature in a patch release?

[joestringer]

@michi-covalent this partly comes out of my discussion here and around the release note: #25491 (comment) .

I don't think we've strictly documented the bar this should meet or the process to remove features from stable. Practically speaking the quality of the feature with recent bugfixes has been raised to the level that we believe to be "stable" - no known outstanding issues for instance, and users are already running the feature in production. So if we're happy to mark it as stable on the latest branch, all other branches logically would also follow suit.

In general I'm not the biggest fan of retrospectively marking features like this, partly because tracking which micro release brought "stability" is difficult to track, and partly because it encourages a deployment lifecycle where users can stay on older versions and still get newer features. But in this particular case, given the feature maturity that has been met and the lack of documented process to guide us, I'm open to making an exception here.

I also recognize that Nate did a lot of work on improving the policy engine to get this feature to this point, and I think it's worth celebrating his contributions through a well-advertised release note.