Use flatdoc or docute to generate the documentation

[AlexandreBonneau]

Since most of the documentation is already written, perhaps we could upgrade the existing markdown files and use one of the following to generate the documentation page:

• http://ricostacruz.com/flatdoc/
• https://github.com/egoist/docute

[AlexandreBonneau]

Or Mkdocs

[AlexandreBonneau]

Or Esdoc

[AlexandreBonneau]

This issue can be closed since https://docs.autonumeric.org/ has been created a while ago now (using Material for mkdocs).