document the webpack flag

Author: lukesandberg

docs/01-app/03-api-reference/06-cli/create-next-app.mdx

@@ -32,6 +32,7 @@ The following options are available:
 | `--api`                                 | Initialize a project with only route handlers                         |
 | `--src-dir`                             | Initialize inside a `src/` directory                                  |
 | `--turbopack`                           | Force enable Turbopack in generated package.json (enabled by default) |
+| `--webpack`                             | Force enable Webpack in generated package.json                        |
 | `--import-alias <alias-to-configure>`   | Specify import alias to use (default "@/\*")                          |
 | `--empty`                               | Initialize an empty project                                           |
 | `--use-npm`                             | Explicitly tell the CLI to bootstrap the application using npm        |