Updated sh file with comment

examples/generics/generics.sh

@@ -1,3 +1,7 @@
 $ go run generics.go
-keys: [1 2 4]
+keys: [4 1 2]
 list: [10 13 23]
+
+# Note: The order of iteration over map keys is not defined in Go,
+# so different invocations may result in different orders.
+# The output need not necessarily be keys=[1 2 4].