wal: minor typo in wal pkg

Fixes a minor typo in wal.go.
Thanks!

wal/wal.go

@@ -329,7 +329,7 @@ func (w *WAL) cut() error {
 	fpath := path.Join(w.dir, walName(w.seq+1, w.enti+1))
 	ftpath := fpath + ".tmp"
 
-	// create a temp wal file with name sequence + 1, or tuncate the existing one
+	// create a temp wal file with name sequence + 1, or truncate the existing one
 	ft, err := os.OpenFile(ftpath, os.O_WRONLY|os.O_APPEND|os.O_CREATE|os.O_TRUNC, 0600)
 	if err != nil {
 		return err