Complete LuisaRender install instructions.

[ScheiklP]

Hi,
I installed genesis-world via pip, and then compiled LuisaRender.
In the current instructions, the build files never get moved into python's site-packages, so genesis cannot import it.
I added the instructions for installation by linking LuisaRender from genesis/ext to genesis/ext/LuisaRender in python's site-packages dir.

I used this method, because genesis assumes this relative path for LuisaRender, so just adding the .so files to the path does not work. :(

terminate called after throwing an instance of 'std::filesystem::__cxx11::filesystem_error'
  what():  filesystem error: cannot make canonical path: No such file or directory [/home/paul/miniforge3/envs/genesis/lib/python3.10/site-packages/genesis/ext/LuisaRender/build/bin]

Careful, this could conflict with this PR:
Genesis-Embodied-AI/Genesis#163

Best,
Paul

[KafuuChikai]

Hi,

The changes in this PR should not cause any conflicts with Genesis-Embodied-AI/Genesis#163. The mentioned PR provides two options:

• if a system environment variable is set, it will prioritize using that value;
• if not, it will fall back to the default relative path.

Therefore, it does not conflict with the symlink approach.