Code samples should support `s390x` and `ppc64le` archs about docs

[knative-prow]

@cardil: The label(s) kind/feature cannot be applied, because the repository doesn't have them.

In response to this:

docs/.github/workflows/knative-docs-image.yaml

Lines 40 to 54 in c522018

	- name: Build helloworld-go image
	uses: docker/build-push-action@v4
	with:
	push: true
	platforms: linux/amd64,linux/arm64
	context: ./code-samples/serving/hello-world/helloworld-go
	tags: ghcr.io/knative/helloworld-go:latest
	- name: Build autoscale-go image
	uses: docker/build-push-action@v4
	with:
	push: true
	platforms: linux/amd64,linux/arm64
	context: ./docs/serving/autoscaling/autoscale-go
	tags: ghcr.io/knative/autoscale-go:latest

As the code samples are used in our tests, they should support the same range or architectures as we do the tests with. We should add support for s390x and ppc64le archs.

/kind feature

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[cardil]

/kind enhancement

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