Update README.md

Co-authored-by: Ralf Jung <[email protected]>

Author: oli-obk

README.md

@@ -252,7 +252,7 @@ environment variable:
   indicates a pointer that was cast from an integer, so Miri was unable to track
   this pointer.
 * `-Zmiri-compare-exchange-weak-failure-rate=<rate>` changes the failure rate of
-  weak atomic operations. The default is `0.8` (so 4 out of 5 weak ops will fail.
+  `compare_exchange_weak` operations. The default is `0.8` (so 4 out of 5 weak ops will fail).
   You can change it to any value between `0.0` and `1.0`, where `1.0` means it
   will always fail and `0.0` means it will never fail.