The doc about EnvoyFilter is incorrect

[spacewander]

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Bug description

The doc about EnvoyFilter is incorrect

Affected product area (please put an X in all that apply)

[ ] Configuration Infrastructure
[x] Docs
[ ] Installation
[ ] Networking
[ ] Performance and Scalability
[ ] Policies and Telemetry
[ ] Security
[ ] Test and Release
[ ] User Experience

Expected behavior

The doc about EnvoyFilter is correct.

Steps to reproduce the bug

The doc claims that "REPLACE is also supported" for EXTENSION_CONFIG:

api/networking/v1alpha3/envoy_filter.proto

Line 337 in 206821b

// operation: ADD # REPLACE is also supported, and would override a cluster level resource with the same name.

But only Add is supported actually. See:

https://github.com/istio/istio/blob/c25ac2f7ffc75ecef1f45a9294672b10905012c6/pilot/pkg/networking/core/v1alpha3/envoyfilter/extension_configuration_patch.go#L35

Version (include the output of istioctl version --remote and kubectl version)

1.20.0

How was Istio installed?

Environment where bug was observed (cloud vendor, OS, etc)

Additionally, please consider attaching a cluster state archive by attaching
the dump file to this issue.