Add font to bootstrap sub-theme I use drupal 8, and Bootstrap theme. 

I created a sub-theme. 

I would like added one font that I downloaded, to use it in my sub-theme. 

I read contradictory things to realize it. For example that it was enough to create a folder "font" in its sub-theme, and add the font in it, then add it in mytheme.libraries.yml, or that it was necessary to place this font in the folder vendor/ . I am a little lost.

How can it be done?
I followed this guide on Google Fonts to get it to work with my downloaded font. In your case that would be editing your info file to declare that you have fonts assets:

name: Subboot
description: Bootstrap Subtheme
type: theme
base theme: bootstrap
core: 8.x
libraries:
  - subboot/fonts


then edit the libraries.yml in your subtheme, ex. subboot.libraries.yml to add in the following:

fonts:
  css:
    theme:
      //your.domain.com/path/to/font {}