Process for generating Adjacency Graphs

Hi,

Related to PR #63, I would be glad to see the following keyboard layouts:
* BÉPO: https://bepo.fr/wiki/Accueil
* AZERTY as per the norm NF Z71-300 : https://norme-azerty.fr/

But my knowledge for generating the `adjacency_graphs.json` file is very limited.
Can you tell my how to compute such file and help me for adding those layouts?
Or maybe someone could handle that?

Many thanks