Add disclaimer that clarifies scope

[entin-hun]

Dear Fellows,
If I am right with the below, it would have been saved me hours if a Mac non-compatibility disclaimer was shown near the installation steps, so I propose it:

• The CUDA Development Tools doesn't support MacOS, or maybe Intel-based Mac running Mac OSX v. 10.13.
• the script seemingly doesn't accept pure images and videos, but one of the following:
• Colmap
• Blender
• NeRF data
• NeRF-like data (how should they prepared with dataset.json? Like Google NeRFies?)

[guanjunwu]

Thank you very much! But rasterzation of Gaussians is wriiten in CUDA? I think that's a reason why it can achieve real-time rendering speed. Change it to python will decrease training and rendering speed.

What's more, nerf-studio's data processing pipeline can solve your problem about customize datasets