Cleanup bookinfo.md (istio#43)

PR addresses bad rendering of list items and adds a few external links.

Author: douglas-reid

docs/samples/bookinfo.md

@@ -37,36 +37,36 @@ This application is polyglot, i.e., the microservices are written in different l
 {% capture prerequisites %}
 _Note: The following instructions assume that you have access to a kubernetes cluster. To install kubernetes locally, checkout [minikube](https://github.com/kubernetes/minikube)_
 
-1. Clone the istio GitHub repository and start the core Istio services (the istio-manager, the istio-mixer, and the istio ingress controller).
-
-```bash  
-git clone https://github.com/istio/istio
-cd istio
-kubectl apply -f ./kubernetes/istio-install
-```
-
-   _Note: the current version of the bookinfo application MUST use the `default` Kubernetes namespace._
+1. Clone the istio GitHub repository and start the core Istio services (the istio-manager, the [Mixer](https://istio.io/docs/concepts/mixer.html), and the istio ingress controller).
 
-2. If you would like to view the metrics collected by Istio proxies, you need to install the Prometheus addon and start a Grafana service as well.
+   ```bash
+   git clone https://github.com/istio/istio
+   cd istio
+   kubectl apply -f ./kubernetes/istio-install
+   ```
 
-```bash
-kubectl apply -f ./kubernetes/addons/
-```
+   _Note: the current version of the bookinfo application MUST use the `default` Kubernetes namespace._ 
 
+1. If you would like to view the metrics collected by Istio proxies, you need to install the [Prometheus](https://prometheus.io/) addon and start a [Grafana](https://grafana.com/) service as well.
+   
+   ```bash
+   kubectl apply -f ./kubernetes/addons/
+   ```
+
    The Grafana image provided as part of this sample contains a built-in Istio-dashboard that you can access from:
 
-```
-http://<grafana-svc-external-IP>:3000/dashboard/db/istio-dashboard
-```
+   ```
+   http://<grafana-svc-external-IP>:3000/dashboard/db/istio-dashboard
+   ```
 
    > The addons yaml files contain services configured as type LoadBalancer. If services are deployed with type NodePort,
    > start kubectl proxy, and edit Grafana's Istio-dashboard to use the Envoy proxy. Access Grafana via kubectl proxy:*
 
    ```
    http://127.0.0.1:8001/api/v1/proxy/namespaces/<ns>/services/grafana:3000/dashboard/db/istio-dashboard
    ```
-
-2. Install the [istioctl](../reference/istioctl.md) CLI, which provides a
+   
+1. Install the [istioctl](../reference/istioctl.md) CLI, which provides a
    convenient way to apply routing rules and policies for upstreams. The
    [istio.VERSION](https://github.com/istio/istio/blob/master/istio.VERSION) file includes the download location of 
    three OS-specific binaries: `istioctl-osx`, `istioctl-win.exe`,