Adjust i18n.md to focus on locale idempotency feature only

Remove references to bin/dev automatic precompile hook coordination,
as that feature will be in a separate PR.

Author: justin808

docs/building-features/i18n.md

@@ -21,24 +21,29 @@ You can use [Rails internationalization (i18n)](https://guides.rubyonrails.org/i
 
 3. The locale files must be generated before `yarn build` using `rake react_on_rails:locale`.
 
+   The locale generation task is idempotent - it will skip generation if files are already up-to-date. This makes it safe to call multiple times without duplicate work:
+
+   ```bash
+   bundle exec rake react_on_rails:locale
+   # Subsequent calls will skip if already up-to-date
+   ```
+
+   To force regeneration:
+
+   ```bash
+   bundle exec rake react_on_rails:locale force=true
+   ```
+
    **Recommended: Use Shakapacker's precompile_hook** (Shakapacker 9.3+)
 
-   The idempotent locale generation task can be safely called multiple times and will skip generation if files are already up-to-date. This makes it ideal for use with Shakapacker's `precompile_hook` feature:
+   Configure the idempotent task in `config/shakapacker.yml` to run automatically before webpack:
 
    ```yaml
    # config/shakapacker.yml
    default: &default
-     # Run locale generation before webpack compilation
-     # Safe to run multiple times - will skip if already built
      precompile_hook: 'bundle exec rake react_on_rails:locale'
    ```
 
-   This ensures locale files are always generated before webpack runs, whether in development, production, or CI. To force regeneration:
-
-   ```bash
-   bundle exec rake react_on_rails:locale force=true
-   ```
-
    **Alternative: Manual coordination**
 
    For development, you can adjust your startup scripts (`Procfile`s) to run `bundle exec rake react_on_rails:locale` before running any Webpack watch process (`yarn run build:development`).