Updated dockerfile and readme

Dockerfile

@@ -1,10 +1,11 @@
 FROM alpine:3.7
 LABEL maintainer="quentin.mcgaw@gmail.com" \
       description="Run the latest StackEdit server in a Docker container" \
+      download="179MB" \
       size="581MB" \
       ram="340MB-500MB" \
+      cpu_usage="Very low" \
       github="https://github.com/qdm12/stackedit-docker"
-EXPOSE 8080
 RUN apk add -q --progress --update --no-cache git nodejs && \
     git clone https://github.com/benweet/stackedit.git && \
     cd stackedit && \
@@ -12,6 +13,8 @@ RUN apk add -q --progress --update --no-cache git nodejs && \
             Dockerfile LICENSE README.md && \
     npm --silent install && \
     npm --silent run build && \
-    apk del -q --progress --purge git
+    apk del -q --progress --purge git ** \
+    rm -rf /var/cache/apk/*
+EXPOSE 8080
 WORKDIR /stackedit
 ENTRYPOINT npm start

README.md

@@ -13,7 +13,9 @@ Stackedit build:
 [![](https://images.microbadger.com/badges/image/qmcgaw/stackedit.svg)](https://microbadger.com/images/qmcgaw/stackedit "Get your own image badge on microbadger.com")
 [![](https://images.microbadger.com/badges/version/qmcgaw/stackedit.svg)](https://microbadger.com/images/qmcgaw/stackedit "Get your own version badge on microbadger.com")
 
-This image is **581 MB** and consumes **340MB-500MB** of RAM
+| Download size | Image size | RAM usage | CPU usage |
+| --- | --- | --- | --- |
+| 179MB | 581MB | 310MB | Very low |
 
 It is based on:
 - [Stackedit](https://github.com/benweet/stackedit)