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/bootstrap-os.md

@@ -48,11 +48,13 @@ The `kubespray-defaults` role is expected to be run before this role.
 
 Remember to disable fact gathering since Python might not be present on hosts.
 
-    - hosts: all
-      gather_facts: false  # not all hosts might be able to run modules yet
-      roles:
-         - kubespray-defaults
-         - bootstrap-os
+```yaml
+- hosts: all
+  gather_facts: false  # not all hosts might be able to run modules yet
+  roles:
+    - kubespray-defaults
+    - bootstrap-os
+```
 
 ## License