Is there any tutorial for C++ API?

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### My Question

Hi Open3D team!

Open3D Python API seems to be very well-documented with detailed tutorials for each module.
On the other hand, the C++ API seems to only have a doxygen website and there are no tutorials provided.

Is this intended?

Many thanks in advance, and excellent work!