[Pedometer 3.0.0]

### Description
Just add in the documentation the need to request permission for Activity recognition with the help of permission handler package
This is the code I put in the main.dart else it will always return registerListener fail (1) etc...
```
await Permission.activityRecognition.request();
if (await Permission.activityRecognition.isDenied) {
await Permission.activityRecognition.request();
}
```

Start by locating the Pedometer 3.0.0 usage documentation and its setup section; the issue does not name a documentation file. Add the requirement to request Activity recognition permission with the permission handler package, using the main.dart example in the issue, and confirm the documented setup addresses registerListener failures.

Written by the indexing model from the issue text.