Update instruction to natively(locally) run Celery service

[candleindark]

See commit for details

[candleindark]

Don't know why the build-image test failed. Don't have a permission to re-run it. It could be a glitch.

Error from the test:

Run docker login -u "$DOCKER_LOGIN" --password-stdin <<<"$DOCKER_TOKEN"
  docker login -u "$DOCKER_LOGIN" --password-stdin <<<"$DOCKER_TOKEN"
  docker build \
    -t dandiarchive/dandiarchive-api \
    -f dev/django-public.Dockerfile \
    .
  shell: /usr/bin/bash -e {0}
  env:
    DOCKER_LOGIN: 
    DOCKER_TOKEN: 
Must provide --username with --password-stdin
Error: Process completed with exit code 1.

[mvandenburgh]

LGTM

I believe CI is failing due to the candleindark/dandi-archive repo not having access to the github actions secrets for logging into docker hub. I'll make and issue for that and merge this PR into another branch within the dandi/dandi-archive repo and see if that fixes it.