[Docs] Update check commands in Japanese documents (#7787)

The Japanese documents included a sample command to check the original document changes. But there was something wrong, so I fixed it.

1 files changed, 1 insertions, 1 deletions

diff --git a/docs/ja/newbs_testing_debugging.md b/docs/ja/newbs_testing_debugging.md
index 9cf5c6520..5ec5811a1 100644
--- a/docs/ja/newbs_testing_debugging.md
+++ b/docs/ja/newbs_testing_debugging.md
@@ -3,7 +3,7 @@
 <!---
   grep --no-filename "^[ ]*git diff" docs/ja/*.md | sh
   original document: ed0575fc8:docs/newbs_testing_debugging.md
-  git diff ed0575fc8 HEAD docs/newbs_testing_debugging.md | cat
+  git diff ed0575fc8 HEAD -- docs/newbs_testing_debugging.md | cat
 -->
 
 カスタムファームウェアをキーボードへ書き込んだら、テストする準備が整います。運が良ければ全て問題なく動作しているはずですが、もしそうでなければこのドキュメントがどこが悪いのか調べるのに役立ちます。