add pre-commit hook to facilitate local testing (#9158)

* add pre-commit hook configuration

* add tmp.md to .gitignore

* describe the use of pre-commit hook in CONTRIBUTING.md

* fix docs/integration.md errors identified by markdownlint

* fix docs/<file>.md errors identified by markdownlint

* docs/azure-csi.md
* docs/azure.md
* docs/bootstrap-os.md
* docs/calico.md
* docs/debian.md
* docs/fcos.md
* docs/vagrant.md
* docs/gcp-lb.md
* docs/kubernetes-apps/registry.md
* docs/setting-up-your-first-cluster.md
* docs/vagrant.md
* docs/vars.md

* fix contrib/<file>.md errors identified by markdownlint

docs/kubernetes-apps/registry.md

@@ -29,8 +29,7 @@ use Kubernetes's `PersistentVolume` abstraction. The following template is
 expanded by `salt` in the GCE cluster turnup, but can easily be adapted to
 other situations:
 
-<!-- BEGIN MUNGE: EXAMPLE registry-pv.yaml.in -->
-``` yaml
+```yaml
 kind: PersistentVolume
 apiVersion: v1
 metadata:
@@ -46,7 +45,6 @@ spec:
     fsType: "ext4"
 {% endif %}
 ```
-<!-- END MUNGE: EXAMPLE registry-pv.yaml.in -->
 
 If, for example, you wanted to use NFS you would just need to change the
 `gcePersistentDisk` block to `nfs`. See
@@ -68,8 +66,7 @@ Now that the Kubernetes cluster knows that some storage exists, you can put a
 claim on that storage. As with the `PersistentVolume` above, you can start
 with the `salt` template:
 
-<!-- BEGIN MUNGE: EXAMPLE registry-pvc.yaml.in -->
-``` yaml
+```yaml
 kind: PersistentVolumeClaim
 apiVersion: v1
 metadata:
@@ -82,7 +79,6 @@ spec:
     requests:
       storage: {{ pillar['cluster_registry_disk_size'] }}
 ```
-<!-- END MUNGE: EXAMPLE registry-pvc.yaml.in -->
 
 This tells Kubernetes that you want to use storage, and the `PersistentVolume`
 you created before will be bound to this claim (unless you have other
@@ -93,8 +89,7 @@ gives you the right to use this storage until you release the claim.
 
 Now we can run a Docker registry:
 
-<!-- BEGIN MUNGE: EXAMPLE registry-rc.yaml -->
-``` yaml
+```yaml
 apiVersion: v1
 kind: ReplicationController
 metadata:
@@ -138,7 +133,6 @@ spec:
         persistentVolumeClaim:
           claimName: kube-registry-pvc
 ```
-<!-- END MUNGE: EXAMPLE registry-rc.yaml -->
 
 *Note:* that if you have set multiple replicas, make sure your CSI driver has support for the `ReadWriteMany` accessMode.
 
@@ -146,8 +140,7 @@ spec:
 
 Now that we have a registry `Pod` running, we can expose it as a Service:
 
-<!-- BEGIN MUNGE: EXAMPLE registry-svc.yaml -->
-``` yaml
+```yaml
 apiVersion: v1
 kind: Service
 metadata:
@@ -164,7 +157,6 @@ spec:
     port: 5000
     protocol: TCP
 ```
-<!-- END MUNGE: EXAMPLE registry-svc.yaml -->
 
 ## Expose the registry on each node
 
@@ -172,8 +164,7 @@ Now that we have a running `Service`, we need to expose it onto each Kubernetes
 `Node` so that Docker will see it as `localhost`. We can load a `Pod` on every
 node by creating following daemonset.
 
-<!-- BEGIN MUNGE: EXAMPLE ../../saltbase/salt/kube-registry-proxy/kube-registry-proxy.yaml -->
-``` yaml
+```yaml
 apiVersion: apps/v1
 kind: DaemonSet
 metadata:
@@ -207,7 +198,6 @@ spec:
           containerPort: 80
           hostPort: 5000
 ```
-<!-- END MUNGE: EXAMPLE ../../saltbase/salt/kube-registry-proxy/kube-registry-proxy.yaml -->
 
 When modifying replication-controller, service and daemon-set definitions, take
 care to ensure *unique* identifiers for the rc-svc couple and the daemon-set.
@@ -219,7 +209,7 @@ This ensures that port 5000 on each node is directed to the registry `Service`.
 You should be able to verify that it is running by hitting port 5000 with a web
 browser and getting a 404 error:
 
-``` console
+```ShellSession
 $ curl localhost:5000
 404 page not found
 ```
@@ -229,7 +219,7 @@ $ curl localhost:5000
 To use an image hosted by this registry, simply say this in your `Pod`'s
 `spec.containers[].image` field:
 
-``` yaml
+```yaml
     image: localhost:5000/user/container
 ```
 
@@ -241,7 +231,7 @@ building locally and want to push to your cluster.
 You can use `kubectl` to set up a port-forward from your local node to a
 running Pod:
 
-``` console
+```ShellSession
 $ POD=$(kubectl get pods --namespace kube-system -l k8s-app=registry \
             -o template --template '{{range .items}}{{.metadata.name}} {{.status.phase}}{{"\n"}}{{end}}' \
             | grep Running | head -1 | cut -f1 -d' ')