[Bug]: Update README to reflect the release of 1.25

[bellkev]

What happened?

Now that Kubernetes 1.25 and Pod Security Admission are released and stable, I thought a couple changes to the README could help newcomers more easily understand the continued relevance and benefits of the project. In particular:

• References to 1.25 like "before it is removed in Kubernetes 1.25" should probably be removed or updated
• Now that Pod Security Admission / Pod Security Standards are stable, it could be helpful to address them more prominently in the README. The linked blog does have some great discussion under "What about PodSecurityStandards?", but it could be helpful to have some similar language close to the top of the README too.

I'd be happy to take a stab at these changes in a PR, but I wanted to open this issue first to solicit feedback, as it would require some nontrivial copy changes.

What policy engine were you generating policy for

No response

Relevant log output

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[chrisns]

Hey,
all good points, I've just regained access to this repo after a year so just catching up trying to bring things up to date.
Please do go ahead and raise PRs for those two points!
Thanks!