import but not use

utils/docx2md.go

@@ -8,15 +8,15 @@ import (
 	"encoding/base64"
 	"encoding/xml"
 	"errors"
-	"flag"
+	_ "flag"
 	"fmt"
 	"io"
 	"io/ioutil"
-	"log"
+	_ "log"
 	"os"
 	"path"
 	"path/filepath"
-	"runtime"
+	_ "runtime"
 	"strconv"
 	"strings"