Rem unused refs

documentation/docs/infrastructure/overview.md

@@ -4,10 +4,4 @@
 
 To run project "Piper", you will need your own Jenkins installation, and you need to care for the configuration that is specific to project "Piper". Please follow the [Custom Jenkins Setup guide][resources-custom-jenkins].
 
-[devops-docker-images-cxs-guide]:    https://github.com/SAP/devops-docker-cx-server/blob/master/docs/operations/cx-server-operations-guide.md
-[docker-images]:                     https://hub.docker.com/u/ppiper
-[resources-docker-rate-limit]:       docker-rate-limit.md
 [resources-custom-jenkins]:          customjenkins.md
-[build-agents]:                      https://wiki.jenkins.io/display/jenkins/distributed+builds
-[ssh-documentation]:                 https://www.openssh.com/manual.html
-[jenkins-helm]:                      https://github.com/helm/charts/tree/master/stable/jenkins