Docker files added

front-end/Dockerfile

 FROM node:14-alpine
 
-WORKDIR /usr/src/app
+WORKDIR /app
 
-COPY package*.json ./
+
+COPY ["package.json", "package-lock.json", "./"]
 
 RUN npm install --silent
 
 RUN npm install react-scripts -g --silent
 
-COPY . . 
+COPY . .
 
 EXPOSE 3000