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

learn/learn-kubernetes-master/kiamol/ch11/bulletin-board/docker/Dockerfile

@@ -0,0 +1,16 @@
+FROM node:10.21-alpine3.11 AS builder
+
+WORKDIR /src
+COPY src/package.json .
+RUN npm install
+
+# app
+FROM node:10.21-alpine3.11 
+
+ENV PORT=8080
+EXPOSE 8080
+CMD ["node", "/app/server.js"]
+
+WORKDIR /app
+COPY --from=builder /src/node_modules/ ./node_modules/
+COPY src/ .