docs: clarify verifier use cases

README.md

@@ -22,7 +22,9 @@ tags:
 
 ## 🌐 Why CodeVerifier?
 
-CodeVerifier evaluates a code state and returns a verdict, a brief explanation, and supporting line ranges. It covers both competitive-programming submissions and repository code.
+Execution provides reliable feedback, but it often arrives too late for large candidate pools, online policy updates, and repository workflows. CodeVerifier supplies timely reward signals for reinforcement learning with verifiable rewards (RLVR) and candidate search, as well as rapid quality feedback for filtering generated training data before a full test run.
+
+Rather than returning only a scalar score, CodeVerifier produces a verdict, a brief explanation, and supporting code regions for complete programs, intermediate edits, and repository code states. It learns these judgments from historical execution outcomes and successful repairs through evidence projection and RVPG.
 
 ## ✨ Highlights