update book code

eBook/examples/chapter_9/book/book_main/main.go

@@ -0,0 +1,14 @@
+package main
+
+import (
+	"fmt"
+	"book/pack1"
+)
+
+func main() {
+	var test1 string
+	test1 = pack1.ReturnStr()
+	fmt.Printf("ReturnStr from package1: %s\n", test1)
+	fmt.Printf("Integer from package1: %d\n", pack1.Pack1Int)
+	//fmt.Printf("Float from package1: %f\n", pack1.pack1Float)
+}