Update README.md

Author: josemoracard

exercises/019-digital_clock/README.md

@@ -16,7 +16,7 @@ digital_clock(150)
 (2, 30)
 ```
 
-For example, if n = 150, then 150 minutes have passed since midnight - i.e. now is 2:30 am. So the function should print 2, 30.
+For example, if n = 150, then 150 minutes have passed since midnight - i.e. now is 2:30 am. So the function should print (2, 30).
 
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