git clone [A repository์ฃผ์]
git subtree add --prefix=[B repository ๋ฃ์ ํ์ผ ์ด๋ฆ] [B repository์ฃผ์][B repository์์ ์ฎ๊ฒจ์ฌ branch ๋ช
]
# ์์
git subtree add --prefix=B_file https://github.com/****/B.git master
git add .
git commit -m "[๋ฉ์ธ์ง ๋ด์ฉ]"
git push