chore(examples): fix typo (#41496)

## Bug

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

## Documentation / Examples

- [ ] Make sure the linting passes by running `pnpm lint`
- [ ] The "examples guidelines" are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)

examples/with-env-from-next-config-js/next.config.js

@@ -5,7 +5,7 @@ const {
 
 // This uses phases as outlined here: https://nextjs.org/docs/#custom-configuration
 module.exports = (phase) => {
-  // when started in development mode `next dev` or `npm run dev` regardless of the value of STAGING environmental variable
+  // when started in development mode `next dev` or `npm run dev` regardless of the value of STAGING environment variable
   const isDev = phase === PHASE_DEVELOPMENT_SERVER
   // when `next build` or `npm run build` is used
   const isProd = phase === PHASE_PRODUCTION_BUILD && process.env.STAGING !== '1'