Change file layout and mention the supported Kubernetes version

images/Dockerfile.s390x

@@ -0,0 +1,20 @@
+# This Dockerfile is used to build the image available on DockerHub
+FROM golang:1.17 as build
+
+# Add everything
+ADD . /usr/src/multus-cni
+
+ENV GOARCH "s390x"
+ENV GOOS "linux"
+
+RUN  cd /usr/src/multus-cni && \
+     ./hack/build-go.sh
+
+# build s390x container
+FROM s390x/python:3-slim
+LABEL org.opencontainers.image.source https://github.com/k8snetworkplumbingwg/multus-cni
+COPY --from=build /usr/src/multus-cni /usr/src/multus-cni
+WORKDIR /
+ADD ./images/entrypoint.sh /
+
+ENTRYPOINT ["/entrypoint.sh"]