README 文中小错误

[chenxinpeng]

SERVER_TMP_DIR=/absolute/path/to/your/tmp/dir mkdir ${SERVER_TMP_DIR} nvidia-docker run -itd --name brpc_faiss_server \ -v ${SERVER_TMP_DIR}:/data/saved_rocksdb_faiss \ -v pwd/:opt/brpc_server \ -p 8330:8330 ${TARGET} /bin/bash

pwd 后拼写误笔，应是：
SERVER_TMP_DIR=/absolute/path/to/your/tmp/dir mkdir ${SERVER_TMP_DIR} nvidia-docker run -itd --name brpc_faiss_server \ -v ${SERVER_TMP_DIR}:/data/saved_rocksdb_faiss \ -v pwd:/opt/brpc_server \ -p 8330:8330 ${TARGET} /bin/bash

[layerism]

谢谢，我回头还要检查里面的东西，我近来重写一版，尽量把东西做的实用一点，这些细节岁末的东西也搞顺滑一下