doc: 添加文档

README.md

@@ -1,3 +1,6 @@
+### INSTALL protoc
+go get -u github.com/golang/protobuf/protoc-gen-go@v1.3.2
+
 ### INSTALL goctl
 GO111MODULE=on go get -u git.i2edu.net/i2/go-zero/tools/goctl