fix: typo

[qhyun2]

What type of PR is this?

/kind documentation

What this PR does / Why we need it:

fixes a typo in the documentation

Which issue(s) this PR fixes:

Closes #

Special notes for your reviewer:

[agones-bot]

Build Failed 😱

Build Id: 62de6d0d-2cd3-427c-9f7b-79a1d6aa4456

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• Cloud Build log download

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[markmandel]

Please ignore the test failure -- our CI suite is a bit borked at the moment.

[agones-bot]

Build Succeeded 👏

Build Id: 53b8e928-996b-4b8d-9a26-a8139ae264bc

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:1.39.0-dev-30994b1-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.39.0-dev-30994b1-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.39.0-dev-30994b1-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.39.0-dev-30994b1-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.39.0-dev-30994b1-amd64
• Linux C++ SDK (build): agonessdk-1.39.0-dev-30994b1-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.39.0-dev-30994b1-amd64.zip

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

• https://30994b1-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/3658/head:pr_3658 && git checkout pr_3658
• helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.39.0-dev-30994b1-amd64