Merge pull request #63 from RyosukeDTomita/feature/gitignore

feat: gitignore global

doc/tools_doc/gitignore.md

@@ -0,0 +1,14 @@
+# gitignoreについて
+
+## サンプル
+
+[言語ごとのサンプル](https://github.com/github/gitignore)
+
+---
+
+## Globalなgitignore
+
+> Patterns which a user wants Git to ignore in all situations (e.g., backup or temporary files generated by the user’s editor of choice) generally go into a file specified by core.excludesFile in the user’s ~/.gitconfig. Its default value is $XDG_CONFIG_HOME/git/ignore. If $XDG_CONFIG_HOME is either not set or empty, $HOME/.config/git/ignore is used instead.
+> [公式ドキュメント](https://git-scm.com/docs/gitignore)
+
+`$XDG_CONFIG_HOMEが設定されていない場合の`初期値は`$HOME/.config/ignore`なので共通でgitignoreにいれたいファイルはここに入れておくのが良さそう。