grepコマンドのを新規追加。
work treeや blobのことhはよくわからない。
Merge branch 'master' of https://github.com/nkkn1008/GitCheetSheet

Conflicts:
	README.md
Merge branch 'master' of https://github.com/nkkn1008/GitCheetSheet

Conflicts:
	README.md
Merge branch 'master' of https://github.com/nkkn1008/GitCheetSheet

Conflicts:
	README.md