Update PeerAuth Documentation to indicate that API Dev is frozen

[whitneygriffith]

I think we should update the API docs to indicate that the API is also frozen and likely to be replaced in ambient

Originally posted by @louiscryan in #3112 (comment)

[whitneygriffith]

@howardjohn should this just be a comment in both the v1beta1 and v1 resource? How do we set the source of truth for istio.io to be v1?

Also, how do I get the warning box similar to what was done for Istio Operator? https://istio.io/latest/docs/setup/install/operator/

[howardjohn]

for istio.io, $mode: none is how to opt-out. So the one without that is the source of truth.

warning box is like

{{< warning >}}
blah
{{< /warning >}}

[whitneygriffith]

@howardjohn I added $mode: none to v1beta1 and removed it from v1 but when make gen is run it reverses the changes, setting $mode: none on v1. Is this because of sync?

[howardjohn]

The sync should only apply to lines after the sync-start line, which is after $mode