[Documentation] Firefox search plugin

[Daniele-Tentoni]

Problem to solve

Search in official documentation site.

Proposed solution

I've createad my Mycroft search plugin. It's here: https://mycroftproject.com/install.html?id=121627&basename=vuetify_search_plg&icontype=ico&name=Vuetify+Search+Plugin. I could update the documentation at https://vuetifyjs.com/en/resources/search-engine accordingly to other browsers.