Add ga-beacon analytics to gendocs scripts

hack/run-gendocs.sh puts ga-beacon analytics link into all md files,
hack/verify-gendocs.sh verifies presence of link.

cluster/juju/bundles/README.md

@@ -195,3 +195,6 @@ for more details about the Kubernetes concepts and terminology.
 
 Having a problem? Check the [Kubernetes issues database](https://github.com/GoogleCloudPlatform/kubernetes/issues)
 for related issues.
+
+
+[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/cluster/juju/bundles/README.md?pixel)]()

cluster/juju/charms/trusty/kubernetes-master/README.md

@@ -99,3 +99,6 @@ to interact with the environment.
 - [Kubernetes issue tracker](https://github.com/GoogleCloudPlatform/kubernetes/issues)
 - [Kubernetes Documenation](https://github.com/GoogleCloudPlatform/kubernetes/tree/master/docs)
 - [Kubernetes releases](https://github.com/GoogleCloudPlatform/kubernetes/releases)
+
+
+[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/cluster/juju/charms/trusty/kubernetes-master/README.md?pixel)]()

cluster/juju/charms/trusty/kubernetes/README.md

@@ -98,3 +98,6 @@ to interact with the environment.
 - [Kubernetes issue tracker](https://github.com/GoogleCloudPlatform/kubernetes/issues)
 - [Kubernetes Documenation](https://github.com/GoogleCloudPlatform/kubernetes/tree/master/docs)
 - [Kubernetes releases](https://github.com/GoogleCloudPlatform/kubernetes/releases)
+
+
+[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/cluster/juju/charms/trusty/kubernetes/README.md?pixel)]()