text: Title: User Guide generation broken on Windows
  Body: env: 
  platform: Windows 10 Pro
  python: 3.7
  RF: master branch
  
  problem: when calling the script ug2html.py to generate the RF user guide, encoutered the following encoding issue, 
  ![image](https://user-images.githubusercontent.com/20227068/224522445-08e798de-37ba-4279-8e0f-3cfa74b00e0e.png)
  this may due to this function:
  
  `doc.userguide.translations.update`
  ```python
  def update(path: Path, content):
      source = path.read_text(encoding='UTF-8').splitlines()
      with open(path, 'w') as file:
          write(source, file, end_marker='.. START GENERATED CONTENT')
          file.write('.. Generated by translations.py used by ug2html.py.\n')
          write(content, file)
          write(source, file, start_marker='.. END GENERATED CONTENT')
  ```
  when calling the open function, does not specify the encoding, the default encoding will be platform dependent. In my case, the encoding cp1252 will be used, this issue happened when write the content that was Bg language and other languages will also meet this issue if cp1252 not support them.
  
  possible solution:  
  specify the encoding to be 'utf-8' when open the file.