Add benchmark overview table

[KennethEnevoldsen]

Add an overview of available benchmarks (similar to what we have for tasks).

[isaac-chung]

Are you envisioning a doc update to list all available benchmarks, a CLI call (like available tasks but for benchmarks), both, or something else?

[KennethEnevoldsen]

Documentation update, we could update the CLI as well, but I would probably start with the docs