Add more examples of tests as per review

subjects/canyoucount/README.md

@@ -2,11 +2,17 @@
 
 ### Instructions
 
-Your program will receive some arguments. Count how many characters they have in total and print them.
+Your program will receive some arguments. Count how many characters they have in total and print them. If the number of arguments is not enough, print 0.
 
 ### Usage
 
 ```console
 $ go run . "hello" "how are you?" | cat -e
-17 $
+17$
+$ go run . "a" | cat -e
+1$
+$ go run . "I am" "myself." | cat -e
+11$
+$ go run . | cat -e
+0$
 ```