Documentation about Module.arguments may need to be improved

The current documentation about `Module.arguments` is not clear enough, see [doc](https://emscripten.org/docs/api_reference/module.html#affecting-execution). You will receive "undefined" if you use `Module.arguments` straight in prejs because the documentation doesn't indicate that you should initialize it first, for example:
```
Module['arguments'].push("-k");
Module['arguments'].push("Image");
Module['arguments'].push("-b");
Module['arguments'].push("minimal.dtb");
Module['arguments'].push("-i");
Module['arguments'].push("rootfs.cpio");
```

Initializing `Module.arguments` before utilizing it in prejs is the proper usage procedure:
```
Module['arguments'] = []
Module['arguments'].push("-k");
Module['arguments'].push("Image");
Module['arguments'].push("-b");
Module['arguments'].push("minimal.dtb");
Module['arguments'].push("-i");
Module['arguments'].push("rootfs.cpio");
```

Related to: #11239