Add a new FAQ, if users re-install vllm-ascend with pip, the `build` folder should be removed first --------- Signed-off-by: rjg-lyh <1318825571@qq.com> Signed-off-by: weiguihua <weiguihua2@huawei.com> Signed-off-by: weiguihua2 <weiguihua2@huawei.com>