code: func (n *Network) concatenateTLSCACertificates() {
  	bundle := &bytes.Buffer{}
  	for _, tlsCertPath := range n.listTLSCACertificates() {
  		certBytes, err := ioutil.ReadFile(tlsCertPath)
  		Expect(err).NotTo(HaveOccurred())
  		bundle.Write(certBytes)
  	}
  	err := ioutil.WriteFile(n.CACertsBundlePath(), bundle.Bytes(), 0660)
  	Expect(err).NotTo(HaveOccurred())
  }
docs: // concatenateTLSCACertificates concatenates all TLS CA certificates into a
  // single file to be used by peer CLI.