modify git-commit.md with comment

iwsed · iwsed · commit 34e8dcff2da9 · 2016-12-08T21:05:57.000+08:00
diff --git a/git-command.md b/git-command.md
@@ -9,7 +9,7 @@ To add new files to the repository or add changed files to staged area:
 To commit them:
 
 ```github
-$ git commit
+$ git commit -m "description"
 ```
 
 To commit unstaged but changed files:
