update 08.1.md (#502)

eBook/08.1.md

@@ -60,7 +60,7 @@ func main() {
 输出结果：
 
 	Map literal at "one" is: 1
-	Map created at "key2" is: 3.14159
+	Map created at "key2" is: 3.141590
 	Map assigned at "two" is: 3
 	Mpa literal at "ten" is: 0