Docs: Remove contributing warning about bug.

[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:

Removed the warning since the bug has now been fixed!

Which issue(s) this PR fixes:

N/A

Special notes for your reviewer:

N/A

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• OWNERS [markmandel]

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[agones-bot]

Build Succeeded 👏

Build Id: 6c680aa8-4492-4b47-b026-fcf790c026a4

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:1.32.0-62f09ef-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.32.0-62f09ef-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.32.0-62f09ef-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.32.0-62f09ef-amd64
• Linux C++ SDK (build): agonessdk-1.32.0-62f09ef-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.32.0-62f09ef-amd64.zip

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

• https://62f09ef-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/3130/head:pr_3130 && git checkout pr_3130
• helm install agones ./install/helm/agones --namespace agones-system --agones.image.release=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.32.0-62f09ef-amd64