fix(examples/with-docker): update env comments (#29972)

This fixes the comment about disabling telemetry. For now it doesn't disable telemetry for `next build` if you uncomment it.

## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`

## Documentation / Examples

- [ ] Make sure the linting passes

examples/with-docker/Dockerfile

@@ -15,13 +15,21 @@ FROM node:16-alpine AS builder
 WORKDIR /app
 COPY --from=deps /app/node_modules ./node_modules
 COPY . .
+
+# Next.js collects completely anonymous telemetry data about general usage.
+# Learn more here: https://nextjs.org/telemetry
+# Uncomment the following line in case you want to disable telemetry during the build.
+# ENV NEXT_TELEMETRY_DISABLED 1
+
 RUN yarn build
 
 # Production image, copy all the files and run next
 FROM node:16-alpine AS runner
 WORKDIR /app
 
 ENV NODE_ENV production
+# Uncomment the following line in case you want to disable telemetry during runtime.
+# ENV NEXT_TELEMETRY_DISABLED 1
 
 RUN addgroup --system --gid 1001 nodejs
 RUN adduser --system --uid 1001 nextjs
@@ -42,9 +50,4 @@ EXPOSE 3000
 
 ENV PORT 3000
 
-# Next.js collects completely anonymous telemetry data about general usage.
-# Learn more here: https://nextjs.org/telemetry
-# Uncomment the following line in case you want to disable telemetry.
-# ENV NEXT_TELEMETRY_DISABLED 1
-
 CMD ["node", "server.js"]