fix bug

markdown/builder.go

@@ -2,7 +2,6 @@ package markdown
 
 import (
 	"bytes"
-	"io"
 	"os"
 	"strings"
 )
@@ -78,6 +77,10 @@ func (m *Builder) SaveToFile(filePath string) error {
 	}
 	defer rf.Close()
 
-	_, err = io.Copy(rf, &m.buf)
+	_, err = rf.WriteString(m.Build())
+	if err != nil {
 		return err
+	}
+
+	return nil
 }