add short instructor bio

Ahoi hoi @bthirion & @srastegarnia,

 could you maybe add a short bio to [your sections](https://main-educational.github.io/material.html#id15) on the general [MAIN educational course page](https://main-educational.github.io/intro.html)? You can also send it to me and I'll add it, no problemo.

Cheers, Peer

