Fix errant quad-tick in docs

cluster/addons/README.md

@@ -21,7 +21,7 @@ manifests on the master server. But still, users are discouraged to do it
 on their own - they should rather wait for a new release of
 Kubernetes that will also contain new versions of add-ons.
 
-Each add-on must specify the following label: ````kubernetes.io/cluster-service: true````.
+Each add-on must specify the following label: ```kubernetes.io/cluster-service: true```.
 Yaml files that do not define this label will be ignored.
 
 The naming convention for Replication Controllers is

docs/getting-started-guides/rkt/README.md

@@ -90,7 +90,7 @@ $ export KUBE_RKT_VERSION=0.5.6
 
 Then you can launch the cluster by:
 
-````shell
+```shell
 $ kube-up.sh
 ```
 
@@ -120,7 +120,7 @@ $ export COREOS_CHANNEL=stable
 
 Then you can launch the cluster by:
 
-````shell
+```shell
 $ kube-up.sh
 ```
 

examples/aws_ebs/README.md

@@ -52,7 +52,7 @@ You should now be able to query your web server:
 ```shell
   $ curl <Pod IP address>
   $ Hello World
-````
+```
 
 
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