Need clarifications to full multi-stage Dockerfile example

[lodinis]

https://github.com/lodinis/nodebestpractices/blob/b8bd67ec16734d60ac208b7309bde995abc097e5/sections/docker/multi_stage_builds.md?plain=1#L79-L121

It seems some permission issues with WORKDIR when using classic (non-buildkit) docker build.
WORKDIR directive creates a new folder with root ownership what causes permission errors on node modules installation:

error Could not write file "/home/node/app/yarn-error.log": "EACCES: permission denied, open '/home/node/app/yarn-error.log'"
error An unexpected error occurred: "EACCES: permission denied, mkdir '/home/node/app/node_modules'".

Detailed WORKDIR permission issue here: moby/moby#36677

I think it's necessary to specify in this paragraph always enabling BuildKit for this multistage Dockerfile build or change Dockerfile example code with:

...
USER node

RUN mkdir -p /home/node/app

WORKDIR /home/node/app
...

[goldbergyoni]

@lodinis Welcome 🌻. Great insight. Would you mind PRing this small and important clarification?