Update the note at the top of the player tracking docs

[roberthbailey]

Make it clearer that it's an alpha feature that will soon be removed.

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
/kind release

What this PR does / Why we need it: The docs are currently confusing as they make it sound like player tracking is in beta (which it is not). Also clarify that player tracking will soon be removed.

Which issue(s) this PR fixes:

Closes #

Special notes for your reviewer:

[agones-bot]

Build Succeeded 🥳

Build Id: 3fca8a1b-7a04-4fae-9adc-4bdfbfcb7011

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:1.43.0-dev-d1b81cd
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.43.0-dev-d1b81cd
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.43.0-dev-d1b81cd-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.43.0-dev-d1b81cd
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.43.0-dev-d1b81cd
• Linux C++ SDK (build): agonessdk-1.43.0-dev-d1b81cd-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.43.0-dev-d1b81cd.zip

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

• https://d1b81cd-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/3974/head:pr_3974 && git checkout pr_3974
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.43.0-dev-d1b81cd

[igooch]

LGTM

[agones-bot]

Build Succeeded 🥳

Build Id: 0bf90fcd-d9ac-4977-9a15-a95c72bceb62

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:1.43.0-dev-676d5b0
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.43.0-dev-676d5b0
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.43.0-dev-676d5b0-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.43.0-dev-676d5b0
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.43.0-dev-676d5b0
• Linux C++ SDK (build): agonessdk-1.43.0-dev-676d5b0-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.43.0-dev-676d5b0.zip

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

• https://676d5b0-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/3974/head:pr_3974 && git checkout pr_3974
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.43.0-dev-676d5b0