Merge pull request #1560 from michelleN/addon-doc

Fix formatting in adding_an_addon.md

docs/contributors/adding_an_addon.md

@@ -7,6 +7,6 @@ To add a new addon to minikube the following steps are required:
   * In order to have `minikube open addons <NEW_ADDON_NAME>` work properly, the `kubernetes.io/minikube-addons-endpoint: <NEW_ADDON_NAME>` label must be added to the appropriate endpoint service (what the user would want to open/interact with).  This service must be of type NodePort.
 
 * To add the addon into minikube commands/VM:
-  * Add the addon with appropriate fields filled into the `Addon` dictionary, see this [Commit](https://github.com/kubernetes/minikube/commit/41998bdad0a5543d6b15b86b0862233e3204fab6#diff-e2da306d559e3f019987acc38431a3e8R133):
-  * Add the addon to settings list, see this [Commit](https://github.com/kubernetes/minikube/commit/41998bdad0a5543d6b15b86b0862233e3204fab6#diff-07ad0c54f98b231e68537d908a214659R89):
+  * Add the addon with appropriate fields filled into the `Addon` dictionary, see this [commit](https://github.com/kubernetes/minikube/commit/41998bdad0a5543d6b15b86b0862233e3204fab6#diff-e2da306d559e3f019987acc38431a3e8R133).
+  * Add the addon to settings list, see this [commit](https://github.com/kubernetes/minikube/commit/41998bdad0a5543d6b15b86b0862233e3204fab6#diff-07ad0c54f98b231e68537d908a214659R89).
 * Rebuild minikube using make out/minikube.  This will put the addon .yaml binary files into the minikube binary using go-bindata.