Small fix in Tpass.C

Tpass.C

@@ -2,5 +2,5 @@ void Tpass(float sqrtSNN, float R)
 {
     float mp = 0.938;
     float t_pass = 4*mp*R/sqrt(sqrtSNN*sqrtSNN - 4*mp*mp);
-    cout << "Tpass = " << t_pass << endl;
+    cout << "Tpass = " << t_pass << " fm/c" << endl;
 }