User and developer documentation for Helm json schema validation

[igooch]

What type of PR is this?

/kind documentation

What this PR does / Why we need it:

Adds user documentation highlighting the addition of the Helm schema validation.

Updates in-place upgrades to "Beta" in the upcoming release documentation as this is for #3766#beta. There is no feature flag for in-place upgrades.

Adds developer documentation on when and how to update the Helm json schema validation file.

Also removes documentation that references fields that do not exist, and adds a field that does exist that was not documented.

Which issue(s) this PR fixes:

Working on #4093

Special notes for your reviewer:

Note that there are two commits, one with the actual changes, and one that is formatting updates only.

There will be an additional to the testing suite in an upcoming PR.

[agones-bot]

Build Failed 😭

Build Id: 217ed5b1-3e04-4048-8893-d669e8ad6f3e

Status: FAILURE

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[agones-bot]

Build Succeeded 🥳

Build Id: 688a24c0-005a-4549-9a97-3dae66f1684a

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:1.47.0-dev-3f220a2
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.47.0-dev-3f220a2
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.47.0-dev-3f220a2-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.47.0-dev-3f220a2
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.47.0-dev-3f220a2
• Linux C++ SDK (build): agonessdk-1.47.0-dev-3f220a2-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.47.0-dev-3f220a2.zip

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

• https://3f220a2-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/4100/head:pr_4100 && git checkout pr_4100
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.47.0-dev-3f220a2

[agones-bot]

Build Succeeded 🥳

Build Id: 86e717ca-21a9-4ccc-8061-e358102cbbc8

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:1.47.0-dev-fc24279
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.47.0-dev-fc24279
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.47.0-dev-fc24279-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.47.0-dev-fc24279
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.47.0-dev-fc24279
• Linux C++ SDK (build): agonessdk-1.47.0-dev-fc24279-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.47.0-dev-fc24279.zip

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

• https://fc24279-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/4100/head:pr_4100 && git checkout pr_4100
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.47.0-dev-fc24279