Migrate to Vuepress

[rakeden]

Is your feature request related to a problem? Please describe.
While we see some limitations in terms of layouti, SEO and we hacked some elemental features, it could be time to move to something more customisable and maintainable

Describe the solution you'd like
An alternative solution is https://vuepress.vuejs.org/

Including a vast variety of plugins to elaborate features for the docs
Localisation: https://vuepress.vuejs.org/guide/i18n.html
Search: https://vuepress.vuejs.org/plugin/official/plugin-search.html#vuepress-plugin-search

[rakeden]

has been completed on the dev-branch