新增learn-kubernetes（https://github.com/yyong-brs/learn-kubernetes）相关文件

learn/learn-kubernetes-master/kiamol/ch21/docker-images/todo-api/Dockerfile

@@ -0,0 +1,15 @@
+FROM node:12.17 AS builder
+
+WORKDIR /src
+COPY package.json .
+RUN npm install
+
+FROM node:12.17-alpine3.11
+
+CMD ["node", "/app/server.js"]
+ENV PORT=80
+EXPOSE 80
+
+WORKDIR /app
+COPY --from=builder /src/node_modules/ /app/node_modules/
+COPY *.js ./