fix: remove bad character from metrics markdown

[code-eg]

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

/kind bug

1. What this PR does / Why we need it: The metrics markdown page is broken due to an extra character

Which issue(s) this PR fixes:

Closes #3976

Special notes for your reviewer:

[google-cla]

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[agones-bot]

Build Succeeded 🥳

Build Id: 30518b30-7379-439b-a31a-e47db1b3ee30

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:1.44.0-dev-1fdaa0e
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.44.0-dev-1fdaa0e
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.44.0-dev-1fdaa0e-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.44.0-dev-1fdaa0e
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.44.0-dev-1fdaa0e
• Linux C++ SDK (build): agonessdk-1.44.0-dev-1fdaa0e-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.44.0-dev-1fdaa0e.zip

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

• https://1fdaa0e-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/3981/head:pr_3981 && git checkout pr_3981
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.44.0-dev-1fdaa0e

[peterzhongyi]

Thanks! But I'm not an approver so I'll also grab someone else.

[igooch]

LGTM. Thanks!

[agones-bot]

Build Succeeded 🥳

Build Id: 54dc0837-7d7e-4d04-b106-ca94af6a7dfd

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:1.44.0-dev-df5d362
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.44.0-dev-df5d362
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.44.0-dev-df5d362-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.44.0-dev-df5d362
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.44.0-dev-df5d362
• Linux C++ SDK (build): agonessdk-1.44.0-dev-df5d362-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.44.0-dev-df5d362.zip

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

• https://df5d362-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/3981/head:pr_3981 && git checkout pr_3981
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.44.0-dev-df5d362