rename 'pattern' to 'hosts' in playbook format.

examples/playbook.yml

@@ -1,6 +1,5 @@
 ---
-- pattern: '*'
-  hosts: '/etc/ansible/hosts'
+- hosts: '*'
   tasks:
   - name: configure template & module variables for future template calls
     action: setup http_port=80 max_clients=200

examples/playbook2.yml

@@ -1,6 +1,5 @@
 ---
-- pattern: '*'
-  hosts: /etc/ansible/hosts
+- hosts: '*'
   tasks:
   - name: config step
     action: setup a=2 b=3 c=4