Modify documents of extra_arguments for both ansible(remote) and ansible-local. (#3423)

website/source/docs/provisioners/ansible-local.html.md

@@ -52,6 +52,11 @@ Optional:
 
 -   `extra_arguments` (array of strings) - An array of extra arguments to pass
     to the ansible command. By default, this is empty.
+    Usage example:
+
+```
+"extra_arguments": [ "--extra-vars \"Region={{user `Region`}} Stage={{user `Stage`}}\"" ]
+```
 
 -   `inventory_groups` (string) - A comma-separated list of groups to which
     packer will assign the host `127.0.0.1`. A value of `my_group_1,my_group_2`

website/source/docs/provisioners/ansible.html.md

@@ -84,7 +84,7 @@ Optional Parameters:
   Usage example:
 
 ```
-"extra_arguments": [ "--extra-vars", "\"Region={{user `Region`}} Stage={{user `Stage`}}\"" ]
+"extra_arguments": [ "--extra-vars", "Region={{user `Region`}} Stage={{user `Stage`}}" ]
 ```
 
 - `ansible_env_vars` (array of strings) - Environment variables to set before running Ansible.