Added Cubxity/AgonesKt to third party libraries

[Cubxity]

What type of PR is this?
/kind documentation

What this PR does / Why we need it:
Added Cubxity/AgonesKt to list of third party libraries. AgonesKt is a Client SDK written in Kotlin to provide developers with ability to interact with Agones SDK.

[agones-bot]

Build Failed 😱

Build Id: 1f255c09-b980-4004-8667-3cd03b665728

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[markmandel]

Flake:

--- FAIL: TestGameServerReadyAllocateReady (148.09s)
    gameserver_test.go:511: 
        	Error Trace:	gameserver_test.go:511
        	Error:      	Received unexpected error:
        	            	timed out waiting for the condition
        	            	waiting for GameServer to be Ready 1614529776/game-serverr58kr
        	            	agones.dev/agones/test/e2e/framework.(*Framework).WaitForGameServerStateWithLogger
        	            		/go/src/agones.dev/agones/test/e2e/framework/framework.go:260
        	            	agones.dev/agones/test/e2e.TestGameServerReadyAllocateReady
        	            		/go/src/agones.dev/agones/test/e2e/gameserver_test.go:510
        	            	testing.tRunner
        	            		/usr/local/go/src/testing/testing.go:1050
        	            	runtime.goexit
        	            		/usr/local/go/src/runtime/asm_amd64.s:1373
        	Test:       	TestGameServerReadyAllocateReady

Hitting retry. Might be time to do another round of flake fixes.

[agones-bot]

Build Succeeded 👏

Build Id: 64775960-c803-4e63-881f-900cfd48e1a7

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

• image: gcr.io/agones-images/agones-controller:1.13.0-37b19c5
• image: gcr.io/agones-images/agones-sdk:1.13.0-37b19c5
• image: gcr.io/agones-images/agones-ping:1.13.0-37b19c5
• Linux C++ SDK (build): agonessdk-1.13.0-37b19c5-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.13.0-37b19c5.zip

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

• https://37b19c5-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/2013/head:pr_2013 && git checkout pr_2013
• helm install ./install/helm/agones --namespace agones-system --name agones --set agones.image.tag=1.13.0-37b19c5

[markmandel]

Thanks! LGTM!

[google-oss-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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

The full list of commands accepted by this bot can be found here.

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• OWNERS [markmandel]

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[google-oss-robot]

New changes are detected. LGTM label has been removed.

[agones-bot]

Build Succeeded 👏

Build Id: cd62043f-9bec-4ef9-8547-a36bdcb703b9

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

• image: gcr.io/agones-images/agones-controller:1.13.0-e492414
• image: gcr.io/agones-images/agones-sdk:1.13.0-e492414
• image: gcr.io/agones-images/agones-ping:1.13.0-e492414
• Linux C++ SDK (build): agonessdk-1.13.0-e492414-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.13.0-e492414.zip

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

• https://e492414-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/2013/head:pr_2013 && git checkout pr_2013
• helm install ./install/helm/agones --namespace agones-system --name agones --set agones.image.tag=1.13.0-e492414