Updated README with cargo generate instructions

[x43romp]

Added detailed usage instructions for using this template using cargo generate tool

[ogoffart]

Thanks for opening a PR.

What is the motivation behind the change?

We went away from cargo generate in #27

[cramhead]

I think cargo-generate has value. I used it as I thought it was more convenient than using the zip file.
Using cargo-generate doesn't mean that you cannot use the zip file approach as defined in the read me.
I've tested it with Mac0S 26.1 (25B78) and cargo 1.93.0-nightly (636800288 2025-10-31). It works fine.