contrib: add cloud-init support for terraform vms (#8394)

* contrib: add cloud-init support for terraform vms

This change enables instance customization via cloud-init,
for example: additional CA certs, custom SSH access etc.

* contrib: update docs for terraform cloud-init

* contrib: disable yamllint in cloud-init

require-starting-space rule breaks cloud-init header

* contrib: documenation formatting

* yamllint: disable comments related checks

* docs: markdown formatting

contrib/terraform/openstack/modules/compute/templates/cloudinit.yaml

@@ -0,0 +1,17 @@
+# yamllint disable rule:comments
+#cloud-config
+## in some cases novnc console access is required
+## it requires ssh password to be set
+#ssh_pwauth: yes
+#chpasswd:
+#  list: |
+#    root:secret
+#  expire: False
+
+## in some cases direct root ssh access via ssh key is required
+#disable_root: false
+
+## in some cases additional CA certs are required
+#ca-certs:
+#  trusted: |
+#      -----BEGIN CERTIFICATE-----