[tor-dev] #3600 tech doc

Hey y'all, For the past little while I've been working on a technical overview doc for #3600 (Prevent redirects from transmitting+storing cookies+identifiers) detailing the problems, scenarios and possible solutions. Please take a look and feel free to comment, edit or add! Link: https://storm.torproject.org/grain/X4nhdNqR9fGRc7sgTefFkg/ best, -Richard