Add s390x CI build status (envoyproxy#35708)

Signed-off-by: namrata-ibm <[email protected]>

README.md

@@ -14,6 +14,7 @@ involved and how Envoy plays a role, read the CNCF
 [![Azure Pipelines](https://dev.azure.com/cncf/envoy/_apis/build/status/11?branchName=main)](https://dev.azure.com/cncf/envoy/_build/latest?definitionId=11&branchName=main)
 [![Fuzzing Status](https://oss-fuzz-build-logs.storage.googleapis.com/badges/envoy.svg)](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:envoy)
 [![Jenkins](https://powerci.osuosl.org/buildStatus/icon?job=build-envoy-static-master&subject=ppc64le%20build)](https://powerci.osuosl.org/job/build-envoy-static-master/)
+[![Jenkins](https://ibmz-ci.osuosl.org/buildStatus/icon?job=Envoy_IBMZ_CI&subject=s390x%20build)](https://ibmz-ci.osuosl.org/job/Envoy_IBMZ_CI/)
 
 ## Documentation