add readme

Author: weisd

generator/readme.md

@@ -0,0 +1,23 @@
+## 使用docker编译protoc-gen-js
+
+运行容器
+
+```
+docker run --rm -it -v /path/to/protobuf-javascript:/data --entrypoint=/bin/bash gcr.io/bazel-public/bazel:latest
+```
+
+在容器中运行
+
+```
+# 编译
+bazel build generator/protoc-gen-js
+
+# 安装protoc
+PB_REL="https://github.com/protocolbuffers/protobuf/releases"
+curl -LO $PB_REL/download/v25.1/protoc-25.1-linux-x86_64.zip
+unzip protoc-25.1-linux-x86_64.zip -d $HOME/.local
+
+# 引用编译好的文件
+protoc --plugin=protoc-gen-js=/data/bazel-bin/generator/protoc-gen-js --js_out=import_style=commonjs:.  /path/to/proto
+
+```