fix: coding style and file format for all example.

eBook/examples/chapter_2/hello_world1.go

@@ -1,7 +1,6 @@
-// hello_world1.go
-package main
-
-func main() {
-	println("Hello", "world")
-}
-
+// hello_world1.go
+package main
+
+func main() {
+	println("Hello", "world")
+}

eBook/examples/chapter_2/version.go

@@ -1,12 +1,13 @@
-package main
-
-import (
-	"fmt"
-	"runtime"
-)
-
-func main() {
-	fmt.Printf("%s", runtime.Version())
-}
-// Output:
-// go1.0.3 or go 1.1
+package main
+
+import (
+	"fmt"
+	"runtime"
+)
+
+func main() {
+	fmt.Printf("%s", runtime.Version())
+}
+
+// Output:
+// go1.0.3 or go 1.1