It's a real debate whether or not to include the field with empty string
to equivalently mean that there isn't any specific comment that the
author wanted to share. To minimize file sizes and improve readability
let's proceed by not specifying default values to fields.
I thought about adding the following convention:
> Current convention is such that if a folder exists but just contains `.gitkeep`, it means that everything that could fall into this folder and isn't existing is considered as verified.
This would be useful for personal git users, but it's an edge case and
would anyway need to precise an overwhole git user gits hash to confirm
a statement at a given gits state.
So let's keep the same convention for every git.
