[LTP] [PATCH] doc: add `--recurse-submodules` when cloning the repo

[Cyril Hrubis]

Hi!
> User could run syscalls testing suite with
> `./kirk -f ltp -r syscalls`,
> but they may not be aware of the submodule `kirk`.
> So I add the `--recurse-submodules` option.

Sounds good to me, we do have a few sumbodules already and it makes
sense to pull them with the initial clone.

Reviewed-by: Cyril Hrubis <chrubis@suse.cz>

-- 
Cyril Hrubis
chrubis@suse.cz