Thanks for pointing it out. I've followed the WordPress-Nginx + Comodo SSL Setup Tutorial. So far the SSL set up is working great, which by the way is a mandatory requirement for those willing to tap HTTP/2.0.
The article HTTP/2 support5 in the DOCS, has no use for me, so not sure what to do within my EE website installation regarding HTTP/2 support.
I've also tried what you describe in your comment, but after restating Nginx and making a CURL request to my domain it still returns HTTP/1.0.
I'll keep watching it, perhaps it's not the right moment yet to put it in action on my website. I'm developing a WordPress + Woocommerce shop powered by EE create --wpfc. So I think its better not to mess up the server's stuff which are working great so far. Thanks for your help!