Fix documentation build

• Fix Flask documentation
• Fix React Styleguidist

Flask documentation build ends with error:

Running Sphinx v3.2.1

Configuration error:
There is a programmable error in your configuration file:

Traceback (most recent call last):
  File "/home/aleksandr/.local/lib/python3.8/site-packages/sphinx/config.py", line 319, in eval_config_file
    execfile_(filename, namespace)
  File "/home/aleksandr/.local/lib/python3.8/site-packages/sphinx/util/pycompat.py", line 89, in execfile_
    exec(code, _globals)
  File "/home/aleksandr/projects/turris-scope/reforis-scope/reforis/docs/source/conf.py", line 16, in <module>
    from docs.source.import_mock import Mock
ModuleNotFoundError: No module named 'docs'

React Styleguidist build ends with error:

./node_modules/foris/form/components/ForisForm.js 128:15
Module parse failed: Unexpected token (128:15)
You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
| 
|     if (forisModuleState.state === API_STATE.ERROR) {
>         return <ErrorMessage message={forisModuleState.data} />;
|     }
|     if (!formState.data) {
 @ ./node_modules/foris/index.js 44:0-56 44:0-56
 @ ./src/lan/LAN.js
 @ ./node_modules/react-styleguidist/lib/loaders/styleguide-loader.js!./node_modules/react-styleguidist/lib/client/index.js
 @ ./node_modules/react-styleguidist/lib/client/index.js
 @ multi ./src/docsUtils/setup.js ./node_modules/react-styleguidist/lib/client/index