ax(mining): replace prose comment with usage example on recordSuccess

AX Principle 2: comments must show HOW with real values, not restate what
the function name already says.

Co-Authored-By: Charon <charon@lethean.io>

pkg/mining/circuit_breaker.go

@@ -177,7 +177,7 @@ func (cb *CircuitBreaker) recordFailure() {
 	}
 }
 
-// recordSuccess records a successful request
+// cb.recordSuccess(stats) // caches result, resets failures; in HalfOpen closes the circuit after SuccessThreshold
 func (cb *CircuitBreaker) recordSuccess(result interface{}) {
 	cb.mu.Lock()
 	defer cb.mu.Unlock()