document locale options and local previews

adds locale examples for the dev server and build commands, a section on previewing a build, and switches the deploy examples from yarn to npm.

Author: dockfries

frontend/README.md

@@ -16,25 +16,41 @@ We welcome contributions to our documentation! Whether you're fixing a typo or a
 
 To preview your changes locally:
 
-1.  **Navigate to the frontend directory:**
-    ```bash
-    cd frontend
-    ```
-2.  **Install dependencies:**
-    ```bash
-    npm install
-    ```
-3.  **Start the development server:**
-    ```bash
-    npm start
-    ```
-    The site will be available at `http://localhost:3000`. Most changes to Markdown files will live-reload in the browser.
+1. **Navigate to the frontend directory:**
+
+   ```bash
+   cd frontend
+   ```
+
+2. **Install dependencies:**
+
+   ```bash
+   npm install
+   ```
+
+3. **Start the development server:**
+
+   ```bash
+   npm start
+   ```
+
+   The site will be available at `http://localhost:3000`. Most changes to Markdown files will live-reload in the browser.
+
+   #### Choosing a locale
+
+   ```bash
+   npm start -- --locale pt-BR    # http://localhost:3000/pt-BR/
+   npm start -- --locale zh-CN    # http://localhost:3000/zh-CN/
+   ```
+
+   `start` accepts a **single** locale — a second `--locale` is silently ignored (the last one wins) — so run one dev server per language on different ports.
 
 ### Adding or Editing Pages
 
 - To **edit** an existing page, find the corresponding `.md` file in `docs/` and make your changes.
 - To **add** a new page, create a new `.md` file in the appropriate subdirectory of `docs/`.
 - Remember to update the **metadata** (front matter) at the top of the file:
+
   ```markdown
   ---
   title: Page Title
@@ -58,29 +74,38 @@ npm i
 ### Local Development
 
 ```bash
-npm start
+npm start                      # default locale
+npm start -- --locale pt-BR    # specific locale
 ```
 
 ### Build
 
 ```bash
-npm run build
+npm run build                                                 # all locales
+npm run build -- --locale pt-BR                               # one locale
+npm run build -- --locale en --locale pt-BR --locale zh-CN    # several locales
 ```
 
 This command generates static content into the `build` directory.
 
+### Local Preview
+
+```bash
+npm run serve
+```
+
 ### Deployment
 
 Using SSH:
 
 ```
-$ USE_SSH=true yarn deploy
+USE_SSH=true npm run deploy
 ```
 
 Not using SSH:
 
 ```
-$ GIT_USER=<Your GitHub username> yarn deploy
+GIT_USER=<Your GitHub username> npm run deploy
 ```
 
 If you are using GitHub pages for hosting, this command is a convenient way to build the website and push to the `gh-pages` branch.