Update docs for Stable Network ID

[markmandel]

What type of PR is this?

Uncomment only one /kind <> line, press enter to put that in a new line, and remove leading whitespace from that line:

/kind breaking
/kind bug
/kind cleanup

/kind documentation

/kind feature
/kind hotfix

What this PR does / Why we need it:

Attempting to alleviate some confusion about Stable Network ID, as it read as if the feature would enable a feature like the ExternalDNS provider -- whereas it's actually only for use within the cluster.

Which issue(s) this PR fixes:

N/A

Special notes for your reviewer:

N/A

[rcreasey]

This helped clarify the situation for our use case. 👍

[agones-bot]

Build Succeeded 👏

Build Id: 5bf1a1da-78f1-4cb8-b692-e53ce51f9098

The following development artifacts have been built, and will exist for the next 30 days:

• image: us-docker.pkg.dev/agones-images/ci/agones-controller:1.32.0-c22185c-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.32.0-c22185c-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.32.0-c22185c-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.32.0-c22185c-amd64
• Linux C++ SDK (build): agonessdk-1.32.0-c22185c-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.32.0-c22185c-amd64.zip

A preview of the website (the last 30 builds are retained):

• https://c22185c-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/3088/head:pr_3088 && git checkout pr_3088
• helm install agones ./install/helm/agones --namespace agones-system --agones.image.release=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.32.0-c22185c-amd64

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: gongmax, markmandel, rcreasey

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• OWNERS [markmandel]

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[agones-bot]

Build Succeeded 👏

Build Id: 5ba48981-66f9-467d-abe3-f67abb65f438

The following development artifacts have been built, and will exist for the next 30 days:

• image: us-docker.pkg.dev/agones-images/ci/agones-controller:1.32.0-7f229f2-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.32.0-7f229f2-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.32.0-7f229f2-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.32.0-7f229f2-amd64
• Linux C++ SDK (build): agonessdk-1.32.0-7f229f2-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.32.0-7f229f2-amd64.zip

A preview of the website (the last 30 builds are retained):

• https://7f229f2-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/3088/head:pr_3088 && git checkout pr_3088
• helm install agones ./install/helm/agones --namespace agones-system --agones.image.release=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.32.0-7f229f2-amd64