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

contrib/network-storage/glusterfs/roles/glusterfs/README.md

@@ -14,12 +14,16 @@ This role performs basic installation and setup of Gluster, but it does not conf
 
 Available variables are listed below, along with default values (see `defaults/main.yml`):
 
-    glusterfs_default_release: ""
+```yaml
+glusterfs_default_release: ""
+```
 
 You can specify a `default_release` for apt on Debian/Ubuntu by overriding this variable. This is helpful if you need a different package or version for the main GlusterFS packages (e.g. GlusterFS 3.5.x instead of 3.2.x with the `wheezy-backports` default release on Debian Wheezy).
 
-    glusterfs_ppa_use: yes
-    glusterfs_ppa_version: "3.5"
+```yaml
+glusterfs_ppa_use: yes
+glusterfs_ppa_version: "3.5"
+```
 
 For Ubuntu, specify whether to use the official Gluster PPA, and which version of the PPA to use. See Gluster's [Getting Started Guide](https://docs.gluster.org/en/latest/Quick-Start-Guide/Quickstart/) for more info.
 
@@ -29,9 +33,11 @@ None.
 
 ## Example Playbook
 
+```yaml
     - hosts: server
       roles:
         - geerlingguy.glusterfs
+```
 
 For a real-world use example, read through [Simple GlusterFS Setup with Ansible](http://www.jeffgeerling.com/blog/simple-glusterfs-setup-ansible), a blog post by this role's author, which is included in Chapter 8 of [Ansible for DevOps](https://www.ansiblefordevops.com/).