Shorten MiMo Git-history check explanation

mimo_v1/README.md

@@ -36,7 +36,7 @@ Includes the full validation run and reruns of repaired tasks. Task `002797` als
 
 ## Reported reward hacks
 
-[Vals AI](https://www.vals.ai/blogs/mimo-reward-hacking) found solution commits in 1,795 of the 2,698 original Code environments. MiMo's re-upload appears to have addressed this: across our 2,509 released tasks, our Git cleanup found no remaining refs or unreachable objects to remove. Our new check looks for commits beyond the task's starting point, including commits hidden from normal Git history.
+[Vals AI](https://www.vals.ai/blogs/mimo-reward-hacking) found solution commits in 1,795 of the 2,698 original Code environments. MiMo's re-upload appears to have addressed this: in the 2,509 tasks we considered, our Git cleanup check (`repository-history-leak`) found no remaining refs or unreachable objects to remove.
 
 **Timestamp hints remained in the re-upload:** our check flagged unusual file timestamps in **975 of the 2,509 tasks**, which could reveal where to make the fix. We added timestamp normalization to all released task Dockerfiles, alongside Git cleanup.