Put a stop to the E_WARNING about failure to open stream

Here's the warning I'm talking about:

```bash
$ ./bin/console generate:html ~/src/basekit/api/application/configs/guzzle/service.json public/
PHP Warning:  file_put_contents(public//data/commands.json): failed to open stream: No such file or directory in /home/h2s/src/interactive-service-description/src/BaseKit/Generator.php on line 80
Generated 355 files
```