##### SUMMARY
The documentation of the module *user* / parameter *shell* states:

https://github.com/ansible/ansible/blob/8edad83ae029d7838a6d6347576d2ddbcce12ad0/lib/ansible/modules/system/user.py#L79

But there are no (shell specific) notes.
##### ISSUE TYPE
- Documentation Report

##### COMPONENT NAME
user / docs

##### ANSIBLE VERSION
devel branch

##### CONFIGURATION
N/A

##### OS / ENVIRONMENT
N/A

##### ADDITIONAL INFORMATION
Either remove the sentence or provide some information in the notes section.

if self.local:
            command_name = 'lusermod'
        else:
            command_name = 'usermod'
        usermod_path = self.module.get_bin_path(command_name, True)
        
        
        if not os.access(usermod_path, os.X_OK):
            return False
        cmd = [usermod_path, '--help']
        (rc, data1, data2) = self.execute_command(cmd, obey_checkmode=False)
        helpout = data1 + data2
        
        lines = to_native(helpout).split('\n')
        for line in lines:
            if line.strip().startswith('-a, --append'):
                return True
        return False
    def modify_user_usermod(self):