Create "Integration Patterns" section in docs

[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:

This sets us up to write the series of guides for Game Server Allocation advanced filtering (#1239), as well as adding
extra guides for integrations such as:

• Websocket servers
• Reusing GameServers
• Canary Testing

And I'm sure more will show up!

Which issue(s) this PR fixes:

N/A

Special notes for your reviewer:

N/A

[agones-bot]

Build Failed 😱

Build Id: 689b4eda-1cbf-42c8-907d-635c8bd07010

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[agones-bot]

Build Failed 😱

Build Id: 0ec0b455-47dc-4f7f-b75d-278fef97606e

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[markmandel]

Tracking Failure I need to fix:

Html Test: Attempt 1
htmltest started at 12:58:36 on /tmp/website
========================================================================
site/docs/integration-patterns/matchmaker-registration/index.html
  target does not exist --- site/docs/integration-patterns/matchmaker-registration/index.html --> ../../../../diagrams/gameserver-reserved.puml.png
========================================================================
✘✘✘ failed in 307.854464ms

[agones-bot]

Build Succeeded 👏

Build Id: bb88761e-3527-498d-9de0-32626658e2ec

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

• image: gcr.io/agones-images/agones-controller:1.17.0-88341a4
• image: gcr.io/agones-images/agones-ping:1.17.0-88341a4
• Linux C++ SDK (build): agonessdk-1.17.0-88341a4-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.17.0-88341a4.zip

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

• https://88341a4-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/2215/head:pr_2215 && git checkout pr_2215
• helm install ./install/helm/agones --namespace agones-system --name agones --set agones.image.tag=1.17.0-88341a4

[roberthbailey]

Just one nit, you can see the extra text on https://88341a4-dot-preview-dot-agones-images.appspot.com/site/docs/integration-patterns/matchmaker-registration/

[agones-bot]

Build Succeeded 👏

Build Id: 50a5ad07-ec5c-4833-a5cc-b6742af37549

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

• image: gcr.io/agones-images/agones-controller:1.17.0-bfaa167
• image: gcr.io/agones-images/agones-ping:1.17.0-bfaa167
• Linux C++ SDK (build): agonessdk-1.17.0-bfaa167-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.17.0-bfaa167.zip

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

• https://bfaa167-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/2215/head:pr_2215 && git checkout pr_2215
• helm install ./install/helm/agones --namespace agones-system --name agones --set agones.image.tag=1.17.0-bfaa167

[google-oss-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• OWNERS [markmandel,roberthbailey]

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