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##### SUMMARY
Add comment_start_string and comment_end_string to template plugin.

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
template

##### ADDITIONAL INFORMATION
In some situation, we need to change comment behavior of template plugin, for an example macros in Zabbix is like {#MACRO}.

<!--- Paste example playbooks or commands between quotes below -->
```yaml
- name: Render a template with "comment_start_string" set to [#
  template:
    src: template.xml.j2
    dest: template.xml
    comment_start_string: "[#"
    comment_end_string: "#]"
```

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from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
class ModuleDocFragment(object):
    
    DOCUMENTATION = r'''
description:
- Templates are processed by the L(Jinja2 templating language,http://jinja.pocoo.org/docs/).
- Documentation on the template formatting can be found in the
  L(Template Designer Documentation,http://jinja.pocoo.org/docs/templates/).
- Additional variables listed below can be used in templates.
- C(ansible_managed) (configurable via the C(defaults) section of C(ansible.cfg)) contains a string which can be used to
  describe the template name, host, modification time of the template file and the owner uid.
- C(template_host) contains the node name of the template's machine.
- C(template_uid) is the numeric user id of the owner.
- C(template_path) is the path of the template.
- C(template_fullpath) is the absolute path of the template.
- C(template_destpath) is the path of the template on the remote system (added in 2.8).