code: def write_sources_file():
      
      file_content = (
          'schemes: '
          'https://github.com/chriskempson/base16-schemes-source.git\n'
          'templates: '
          'https://github.com/chriskempson/base16-templates-source.git'
      )
      file_path = rel_to_cwd('sources.yaml')
      with open(file_path, 'w') as file_:
          file_.write(file_content)
docs: Write a sources.yaml file to current working dir.