Better docker image and docs

Dockerfile

@@ -1,12 +1,23 @@
-FROM node:18-alpine
+FROM node:20-alpine
 WORKDIR /usr/src/app
 
-# Setup Alpine for building "canvas" package
-RUN apk add --no-cache python3 make g++ pkgconfig cairo-dev pango-dev
+# Setup Alpine for canvas
+RUN apk add --no-cache \
+    # Build only
+    python3 g++ make cairo-dev pango-dev \
+    # Runtime
+    cairo pango
 
+# Install deps
 COPY package.json yarn.lock ./
 RUN yarn install
-COPY . .
+
+# Copy required files for server
+COPY ./src ./src
+COPY ./api ./api
+COPY ./js ./js
+
+RUN apk del python3 g++ make cairo-dev pango-dev
 
 EXPOSE 8080
 CMD [ "node", "api/index.js" ]