Added Quickstart section to README

[DarkWanderer]

Added a dozen lines to help new users get over initial new tech complexity

[ngxson]

I disagree with this change, it sound quite ignorant tbh:

1. We also support AMD and Intel GPU, not just CUDA
2. What about Mac users?
3. IIRC ngl is no longer required, GPU is used by default
4. Why adding downloading step, while -hf already does the job?

[ngxson]

If we want to make an easier guide, simply:

1. Make the part "Download pre-built binaries from releases" more prominent
2. Probably mention -hf flag in the example area

[DarkWanderer]

A Quickstart guide by design does not cover all scenarios and simply provides the fastest route to get something working for a new user.

it sound quite ignorant tbh

I will not spend my time on trying to contribute if this is the reviewers' attitude however.