Is your feature request related to a problem? Please describe.
the usage of ConfigParser methods read_config, load_config_file, load_config_files are not straightforward, would be great to clarify that

• parser.read_config is an instance method that could take key-value pairs and override existing parser's config.
• ConfigParser.load_config_file is a class method for loading a single json/yaml file
• ConfigParser.load_config_files is a class method for loading multiple config files and combine the config contents