我有一个~/.janus/带有一堆子模块的git repo .我想添加一个子模块~/.janus/snipmate-snippets/snippets/,但是当我git submodule add <git@github.com:...>在snipmate-snippets目录中运行时,我收到以下错误消息:
You need to run this command from the toplevel of the working tree.
所以问题是:如何在snipmate-snippets目录中添加子模块？