docs: how can ADBC Driver Manifests support be documented

### What would you like help with?

ADBC Driver Manifests are relatively new and only the C++ and Rust driver managers support them. How can we document this in an easy to find and easy to link to place?

We have a nice status table for Drivers but nothing for the ADBC libraries themselves. Could we have a ADBC libraries status page and, if so, what would go on it beyond just Manifests support? Should we document this at all?

Start by reviewing the existing Drivers status table and the ADBC Driver Manifests support in the C++ and Rust driver managers. Determine whether an ADBC libraries status page is warranted and what it should cover beyond Manifest support. Done means proposing a clear, easy-to-find and easy-to-link documentation location and scope.

Written by the indexing model from the issue text.