Update README.rst

```python
def get_upload_filename(upload_name, user):
    # If CKEDITOR_RESTRICT_BY_USER is True upload file to user specific path.
    if getattr(settings, 'CKEDITOR_RESTRICT_BY_USER', False):
        user_path = user.username
    else:
        user_path = ''

    # Generate date based path to put uploaded file.
    date_path = datetime.now().strftime('%Y/%m/%d')

    # Complete upload path (upload_path + date_path).
    upload_path = os.path.join(
        settings.CKEDITOR_UPLOAD_PATH, user_path, date_path)

    if getattr(settings, "CKEDITOR_UPLOAD_SLUGIFY_FILENAME", True):
        upload_name = utils.slugify_filename(upload_name)

    return default_storage.get_available_name(os.path.join(upload_path, upload_name))
```

There's an error in the readmefile.