Merge pull request #579 from watermelo/featue/addCommentForConfig

config/application_config.go

config/base_config.go

config/config_center_config.go

config/consumer_config.go

config/generic_service.go

config/graceful_shutdown.go

config/graceful_shutdown_config.go

config/graceful_shutdown_signal_darwin.go

config/graceful_shutdown_signal_linux.go

config/graceful_shutdown_signal_windows.go

config/instance/metadata_report.go

config/interfaces/config_reader.go

config/metadata_report_config.go

config/method_config.go

config/mock_rpcservice.go

config/protocol_config.go

config/provider_config.go

config/reference_config.go

config/registry_config.go

config/service.go