support Generate basic structs for all kinds of languages.

Usage:

make [all] : generates for all languages supported.
make < go | python | >	: generates for specific language.
make clean : remove all generated files.
make help : show this message.

Makefile

@@ -2,7 +2,7 @@
 # protoc is required:
 # pacman -S protoc
 # apt install protoc
-.PHONY: all go python clean
+.PHONY: all go python clean help
 
 all: go python
 
@@ -16,4 +16,14 @@ python:
 
 clean:
 	-@rm *_pb2.py
-	-@rm *.pb.go
+	-@rm *.pb.go
+
+help:
+	@echo Generate basic structs for all kinds of languages.
+	@echo 
+	@echo Usage:
+	@echo
+	@echo make [all]				: generates for all languages supported.
+	@echo make "< go | python | >	: generates for specific language."
+	@echo make clean				: remove all generated files.
+	@echo make help					: show this message.