Rework the README

[quentinhaenn]

Rework of README file to make it more pleasant :

• badges for binder, coverage and maybe some other things
• Add more example and rework benchmarks
• Rework citations
• think about getting a DOI from ZENODO, or use the one from software heritage

[quentinhaenn]

Added everything mentioned except benchmarks and examples which will be in the example folder.

Closing.