Change flagship example in the Readme

[lorepieri8]

[Opinion-based issue, feel free to close.]

I propose to use the example shown in modeling as the flagship example, for instance on the README.

https://cpmpy.readthedocs.io/en/latest/modeling.html

It is very easy to understand and comprehensive at the same time, while the Sudoku example adds some unnecessary complexity due to the 2D nature.

[tias]

Hi Lorenzo,

you were absolutely right about the README, it was still from the early days of contrasting with other CP languages, rather than explaining the library as is.

We've just pushed our rework of the README and user docs, to be 'first user' friendly.

Kind regards,
Tias