Parameter descriptions (!25) · Merge requests · Bold Hearts / ros2_v4l2_camera

Adds descriptions to parameters with their limits and restrictions. E.g. the following lists all available image sizes for supported formats:
```
  ros2 param describe /v4l2_camera image_size
```
Fixes being able to change image size dynamically, e.g.:
```
  ros2 param set /v4l2_camera image_size '[640, 360]'
```

Parameter descriptions