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.

contrib/git-sync/README.md

@@ -14,3 +14,6 @@ docker run -d GIT_SYNC_REPO=https://github.com/GoogleCloudPlatform/kubernetes GI
 # run a nginx container to serve sync'ed content
 docker run -d -p 8080:80 -v /git-data:/usr/share/nginx/html nginx 
 ```
+
+
+[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/contrib/git-sync/README.md?pixel)]()

contrib/git-sync/demo/README.md

@@ -28,3 +28,6 @@ kubectl services create config/pod.html
 ```
 
 Open the service external ip in your browser
+
+
+[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/contrib/git-sync/demo/README.md?pixel)]()

contrib/git-sync/demo/blog/content/about.md

@@ -7,3 +7,6 @@ title = "about"
 ## A headline
 
 Some content about the blog.
+
+
+[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/contrib/git-sync/demo/blog/content/about.md?pixel)]()

contrib/git-sync/demo/blog/content/post/first.md

@@ -7,3 +7,6 @@ title = "first"
 ## first port
 
 This is the first post.
+
+
+[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/contrib/git-sync/demo/blog/content/post/first.md?pixel)]()

contrib/git-sync/demo/hugo/README.md

@@ -10,3 +10,6 @@ docker build -t hugo .
 # run the hugo container
 docker run -e HUGO_BASE_URL=example.com -v /path/to/md:/src -v /path/to/html:/dest hugo
 ``
+
+
+[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/contrib/git-sync/demo/hugo/README.md?pixel)]()