##### SUMMARY
If a module sets `add_file_common_args=True` when calling `AnsibleModule`, all elements from [FILE_COMMON_ARGUMENTS](https://github.com/ansible/ansible/blob/e9d29b1fe4285d90d7a4506b80260a9e24c3bcea/lib/ansible/module_utils/basic.py#L229-L257) are included in the argument spec. The [files document fragment](https://github.com/ansible/ansible/blob/e9d29b1fe4285d90d7a4506b80260a9e24c3bcea/lib/ansible/plugins/doc_fragments/files.py#L15-L80) only documents a subset of them, though. Missing are:
 - src
 - follow
 - force
 - content
 - backup
 - remote_src
 - regexp
 - delimiter
 - directory_mode

Most module authors using `add_file_common_args=True` are probably not aware that their modules have these options as well.

I don't think these extra options should be added by default if `add_file_common_args=True` is specified.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
lib/ansible/module_utils/basic.py

##### ANSIBLE VERSION
```
devel
```

src=dict(),  
    follow=dict(type='bool', default=False),  
    force=dict(type='bool'),
    
    
    
    content=dict(no_log=True),  
    backup=dict(),  
    remote_src=dict(),  
    regexp=dict(),  
    delimiter=dict(),  
    directory_mode=dict(),  
    unsafe_writes=dict(type='bool'),  
)
PASSWD_ARG_RE = re.compile(r'^[-]{0,2}pass[-]?(word|wd)?')
MODE_OPERATOR_RE = re.compile(r'[+=-]')
USERS_RE = re.compile(r'[^ugo]')
PERMS_RE = re.compile(r'[^rwxXstugo]')
_PY3_MIN = sys.version_info[:2] >= (3, 5)
_PY2_MIN = (2, 6) <= sys.version_info[:2] < (3,)
_PY_MIN = _PY3_MIN or _PY2_MIN
if not _PY_MIN:
    print(
        '\n{"failed": true, '
        '"msg": "Ansible requires a minimum of Python2 version 2.6 or Python3 version 3.5. Current version: %s"}' % ''.join(sys.version.splitlines())
    )
    sys.exit(1)
#
#
def get_platform():