Adding Contrail/Tungsten Fabric to the add-on list (#12865)

* Update addons.md

* Update addons.md

content/en/docs/concepts/cluster-administration/addons.md

@@ -26,6 +26,7 @@ Add-ons in each section are sorted alphabetically - the ordering does not imply
 * [Cilium](https://github.com/cilium/cilium) is a L3 network and network policy plugin that can enforce HTTP/API/L7 policies transparently. Both routing and overlay/encapsulation mode are supported.
 * [CNI-Genie](https://github.com/Huawei-PaaS/CNI-Genie) enables Kubernetes to seamlessly connect to a choice of CNI plugins, such as Calico, Canal, Flannel, Romana, or Weave.
 * [Contiv](http://contiv.github.io) provides configurable networking (native L3 using BGP, overlay using vxlan, classic L2, and Cisco-SDN/ACI) for various use cases and a rich policy framework. Contiv project is fully [open sourced](http://github.com/contiv). The [installer](http://github.com/contiv/install) provides both kubeadm and non-kubeadm based installation options.
+* [Contrail](http://www.juniper.net/us/en/products-services/sdn/contrail/contrail-networking/), based on [Tungsten Fabric](https://tungsten.io), is a open source, multi-cloud network virtualization and policy management platform. Contrail and Tungsten Fabric are integrated with orchestration systems such as Kubernetes, OpenShift, OpenStack and Mesos, and provide isolation modes for virtual machines, containers/pods and bare metal workloads.
 * [Flannel](https://github.com/coreos/flannel/blob/master/Documentation/kubernetes.md) is an overlay network provider that can be used with Kubernetes.
 * [Knitter](https://github.com/ZTE/Knitter/) is a network solution supporting multiple networking in Kubernetes.
 * [Multus](https://github.com/Intel-Corp/multus-cni) is a Multi plugin for multiple network support in Kubernetes to support all CNI plugins (e.g. Calico, Cilium, Contiv, Flannel), in addition to SRIOV, DPDK, OVS-DPDK and VPP based workloads in Kubernetes.