Concurrency proxyConfig definition need updating

[RicHincapie]

As per the latest docs here https://istio.io/latest/docs/reference/config/networking/proxy-config/#ProxyConfig, concurrency settings are described as

The number of worker threads to run. If unset, defaults to 2. If set to 0, this will be configured to use all cores on the machine using CPU requests and limits to choose a value, with limits taking precedence over requests.

But, at code level here https://github.com/istio/api/blob/94d8c5322f50ffb0c70adb321c62603d1180e413/mesh/v1alpha1/proxy.proto#L458 says:

The number of worker threads to run.
// If unset, this will be automatically determined based on CPU requests/limits.
// If set to 0, all cores on the machine will be used.

Based on this PR istio/istio#43865, the behavior is the one described at code level.

[kfaseela]

i think, this comes from: https://github.com/istio/api/blob/94d8c5322f50ffb0c70adb321c62603d1180e413/networking/v1beta1/proxy_config.proto#L119

[ericvn]

Note that istio.io reflects the 1.21 branches of the various repos as it is for Istio release 1.21. preliminary.istio.io reflects the master branches as it is being setup for the 1.22 release. It may be that something wasn't cherry-picked to release-1.21, or it could be that the master branch includes 1.22 changes which should not be reflected in istio.io. If the change should be reflected for 1.21 at istio.io, then the change should be cherry-picked to the release-1.21 branch. Note that while we update preliminary.istio.io on a daily basis, we typically only update istio.io when a new patch is released (so the cherry-pick may have happened but we haven't done the doc update).

[ericvn]

Looking, the code change is in the 1.22 stream so I believe updating in the master branch of istio/api and then reflected in preliminary.istio.io is correct (until 1.22.0 is released when it will be reflected at istio.io).