readme: describe the space card in client-facing terms

README.md

@@ -25,12 +25,11 @@ tags:
 
 # CADGenBench Leaderboard
 
-A benchmark for AI-driven CAD generation: how well can a model turn a
+A benchmark for AI-driven CAD generation: how well can a system turn a
 textual or visual description of a mechanical part into a valid,
 geometrically correct 3D model?
 
-In active development under
-`HuggingAI4Engineering/cadgenbench-leaderboard`; will flip to public
-once the eval handler is wired up and the real dataset is in place.
-Reference shape inspired by
-[`adyen/DABstep`](https://huggingface.co/spaces/adyen/DABstep).
+Browse the **Leaderboard** tab for ranked submissions, or upload your
+own STEP files on the **Submit** tab: the Space runs the eval and
+publishes a row with a per-submission report. The **About** tab covers
+the scoring axes and links to the benchmark code and datasets.