Adding section for authentication on Azure

Ready to be merged, however, will be revisited at a later date to include alternate authentication processes
Co-Authored-By: NMaanav Dalal <maanavdalal@gmail.com>
Co-Authored-By: NMohona Ahmed <t-moahme@microsoft.com>

content/docs/azure/authentication.md

++++
+title = "Restricting Access & Authentication "
+description = "Restrict access of your deployment to specified IP addresses"
+weight = 100
++++
+
+This section shows how to restrict access to only certain IP addresses for your LoadBalancer Service. At a later date, it will also include formal authentication through Azure. This method is not the most ideal way to secure your Kubernetes cluster, as it requires that you access the service from the same IP address every time. This process was adapted from [this guide](https://kubernetes.io/docs/tasks/access-application-cluster/configure-cloud-provider-firewall/#restrict-access-for-loadbalancer-service).
+
+
+When using a Service with `spec.type: LoadBalancer`, you can specify the IP ranges that are allowed to access the load balancer by using `spec.loadBalancerSourceRanges`. This is currently supported on all major cloud providers. 
+
+### Editing the LoadBalancer service
+Use the `kubectl edit svc <loadbalancer-name> -n kubeflow` to add your source ranges. Pressing `i` will allow you to insert text, and `esc` followed by `:wq` will allow you to write and quit out of the text editor.
+#### Internal subnet access
+Assuming 10.0.0.0/8 is the address for the internal subnet, a load balancer will be created such that the deployment is only accessible from internal Kubernetes cluster IPs. This will not allow clients from outside your Kubernetes cluster to access the load balancer.
+
+```
+apiVersion: v1
+kind: Service
+metadata:
+  name: myapp
+spec:
+  ports:
+  - port: 8765
+    targetPort: 9376
+  selector:
+    app: example
+  type: LoadBalancer
+  loadBalancerSourceRanges:
+  - 10.0.0.0/8
+```
+#### External IP Addresses 
+In the following example, a load balancer will be created that is only accessible to clients with IP addresses from 130.211.204.1 and 130.211.204.2.
+```
+apiVersion: v1
+kind: Service
+metadata:
+  name: myapp
+spec:
+  ports:
+  - port: 8765
+    targetPort: 9376
+  selector:
+    app: example
+  type: LoadBalancer
+  loadBalancerSourceRanges:
+  - 130.211.204.1/32
+  - 130.211.204.2/32
+```