Trivial: Fix the pep8 warning

The yaml should start with "---"

Change-Id: Ibb810c8cbbf129d99250879584c19fab5f5ec3da

examples/playbook.yml

@@ -1,3 +1,4 @@
+---
 - name: Basic host setup
   hosts: "hosts"
   user: root

tasks/openstack_hosts_configure_apt.yml

@@ -1,3 +1,4 @@
+---
 # Copyright 2017, Rackspace US, Inc.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");

tasks/openstack_hosts_configure_dnf.yml

@@ -1 +1,2 @@
+---
 openstack_hosts_configure_yum.yml

tests/ansible-role-requirements.yml

@@ -1,3 +1,4 @@
+---
 - name: apt_package_pinning
   src: https://git.openstack.org/openstack/openstack-ansible-apt_package_pinning
   scm: git

zuul.d/project.yaml

@@ -1,3 +1,4 @@
+---
 # Copyright 2017, Rackspace US, Inc.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");