Add more examples of tests as per review

subjects/canyoucount/README.md

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+## canyoucount
+
+### Instructions
+
+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$
+$ go run . "a" | cat -e
+1$
+$ go run . "I am" "myself." | cat -e
+11$
+$ go run . | cat -e
+0$
+```