docs(docker): update base image to node:20-alpine in Docker examples (#83125)
This PR updates all example Dockerfiles that were using `node:18-alpine`
to `node:20-alpine`
to align with current LTS and address known issues in Node 18 images.
- examples/with-docker/Dockerfile
- examples/with-docker-compose/next-app/prod.Dockerfile
- examples/with-docker-compose/next-app/dev.Dockerfile
- examples/with-docker-multi-env/docker/development/Dockerfile
- examples/with-docker-multi-env/docker/production/Dockerfile
- examples/with-docker-multi-env/docker/staging/Dockerfile
I verified local builds for each example. No behavior changes;
docs/examples only.
https://github.com/vercel/next.js/issues/78465
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Co-authored-by: Joseph <joseph.chamochumbi@vercel.com>