update dockerfile in readme

README.md

@@ -31,12 +31,12 @@ The site can also be built and ran inside a docker container when you are in the
 ## Dockerfile
 
 ```dockerfile
-FROM node:10-alpine3.9 as npmpackages
+FROM node:18-alpine3.15 as npmpackages
 WORKDIR /app
 COPY package.json .
 RUN npm install
 
-FROM node:10-alpine3.9 as builder
+FROM node:18-alpine3.15 as builder
 WORKDIR /app
 COPY --from=npmpackages /app /app
 COPY . .
@@ -45,6 +45,7 @@ RUN npm run build
 FROM nginx:1.17.10-alpine
 RUN rm -r /usr/share/nginx/html/
 COPY --from=builder /app/_site/ /usr/share/nginx/html/
+
 ```
 ### Ouroboros