C++ Documentation

This is only a question, and a potential feature request.

I have been using Open Spiel for developing an Alpha Zero agent for a particular game.
Due to the game's potential complexity. I am considering to use reverb as a mechanism for **Seperation of Concerns**, and to scale the Alpha Zero algorithm.

- To be more precise, the actors that generate the trajectories are written in C++. Each actor will be on a separate thread/machine on a potential HPC cluster.
- I have also a learner written in Python that casually extracts data from the actors.

Unfortunately, this is not straightforwards as there appears to be a lack of C++ documentation. With that I have a question and a potential feature request:
1. Does reverb support calling client-side code from C++? In particular that would be the logic to insert trajectories into the server?
2. If it is so, I think adding C++ would be great.

No files or tests are named. Start by checking whether Reverb exposes a C++ client path for inserting trajectories, then review the existing client documentation and Python learner usage. Done means the C++ support question is answered and any supported workflow is documented, or the needed feature is clearly scoped.

Written by the indexing model from the issue text.