message: Keep line that states why we should copy the repo skeleton first
diff: @@ -59,7 +59,7 @@ Once the host build is complete, we are ready to build our image. The following
  FROM node:14-buster-slim
  WORKDIR /app
  -
  +# Copy repo skeleton first, to avoid unnecessary docker cache invalidation.
  # The skeleton contains the package.json of each package in the monorepo,
  # and along with yarn.lock and the root package.json, that's enough to run yarn install.
  COPY yarn.lock package.json packages/backend/dist/skeleton.tar.gz ./
  