Update "Local Development" documents

[aLekSer]

Document state changing feature of local SDK server.

For #958 .

[agones-bot]

Build Failed 😱

Build Id: aea0b8f7-1a17-4f3b-9090-2033cd647409

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[agones-bot]

Build Succeeded 👏

Build Id: 0c412a58-2616-47f6-b195-9766845ee881

The following development artifacts have been built, and will exist for the next 30 days:

• image: gcr.io/agones-images/agones-controller:1.1.0-4310adb
• image: gcr.io/agones-images/agones-sdk:1.1.0-4310adb
• image: gcr.io/agones-images/agones-ping:1.1.0-4310adb
• Linux C++ SDK (build): agonessdk-1.1.0-4310adb-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.1.0-4310adb.zip

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

• https://4310adb-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/GoogleCloudPlatform/agones.git pull/1159/head:pr_1159 && git checkout pr_1159
• helm install install/helm/agones --namespace agones-system --name agones --set agones.image.tag=1.1.0-4310adb

[google-oss-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aLekSer, roberthbailey

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• OWNERS [roberthbailey]

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[agones-bot]

Build Succeeded 👏

Build Id: 4cf692a6-f916-4052-b72f-33f3d42f1f3a

The following development artifacts have been built, and will exist for the next 30 days:

• image: gcr.io/agones-images/agones-controller:1.1.0-8b1fa5a
• image: gcr.io/agones-images/agones-sdk:1.1.0-8b1fa5a
• image: gcr.io/agones-images/agones-ping:1.1.0-8b1fa5a
• Linux C++ SDK (build): agonessdk-1.1.0-8b1fa5a-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.1.0-8b1fa5a.zip

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

• https://8b1fa5a-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/GoogleCloudPlatform/agones.git pull/1159/head:pr_1159 && git checkout pr_1159
• helm install install/helm/agones --namespace agones-system --name agones --set agones.image.tag=1.1.0-8b1fa5a