update book code

eBook/exercises/chapter_7/split_string.go

@@ -0,0 +1,16 @@
+package main
+
+import "fmt"
+
+func main() {
+	str := "Google"
+	for i:=0; i <= len(str); i++ {
+		a, b := Split(str, i)
+		fmt.Printf("The string %s split at position %d is: %s / %s\n", str, i, a, b)
+	}
+	
+}
+
+func Split(s string, pos int) (string, string) {
+	return s[0:pos], s[pos:]
+}