How can we contribute to the project?

Hey guys, I'm having problems running the watcher. Sometimes the `$ret` returns false and it is triggered an undefined index at [that line](https://github.com/hyperf/watcher/blob/master/src/Watcher.php#L80). I created a fork here with the change below and it works.

```php
$command = sprintf('%s %s/vendor/hyperf/watcher/collector-reload.php %s', $this->option->getBin(), BASE_PATH, $file);
$ret = exec($command);
$code = $ret['code'] ?? null;
```
I’d like to know how I can help make this change to this great tool.
Thanks in advance.