fix Dockerfile

Dockerfile

@@ -2,10 +2,8 @@ FROM node:alpine
 RUN mkdir /peer-server
 WORKDIR /peer-server
 COPY bin ./bin
+COPY dist ./dist
 COPY package.json .
-COPY src ./src
-COPY config ./config
-COPY app.json .
 RUN npm install
 EXPOSE 9000
 ENTRYPOINT ["node", "bin/peerjs"]