Solve pydocstyle errors

[orviz]

Current set of errors:

openapi_server/controllers/security_controller_.py:1 at module level:
        D100: Missing docstring in public module
openapi_server/controllers/app_controller.py:1 at module level:
        D100: Missing docstring in public module
openapi_server/controllers/app_controller.py:9 in public function `get_ml_app_by_name`:
        D400: First line should end with a period (not 'e')
openapi_server/controllers/app_controller.py:21 in public function `update_ml_app`:
        D400: First line should end with a period (not 'p')
openapi_server/controllers/app_controller.py:21 in public function `update_ml_app`:
        D401: First line should be in imperative mood (perhaps 'Update', not 'Updated')
openapi_server/controllers/__init__.py:1 at module level:
        D104: Missing docstring in public package

Dependencies: pip install pydocstyle

Reference: https://github.com/mitmproxy/pdoc