Update README.md

[dmikey]

missing init, then update will pull ggml

[leejet]

In fact, for those who clone the repository using git clone --recursive https://github.com/leejet/stable-diffusion.cpp, the init doesn't really make sense. However, to prevent any potential mistakes from people not including the --recursive parameter, I've decided to merge this PR.

[dmikey]

Thanks! That's me! The guy that only follows half the directions :)