Fixed dead links and updated some to https#218

Merged

brentyi merged 3 commits intocs231n:masterfrom

MaxTranced:patch-1

Apr 6, 2020

Commits on Nov 15, 2019

Fixed dead link to "EricsBroadcastingDoc"
MaxTranced
authored

Commits on Nov 27, 2019

http -> https where possible and fixed more broken links
MaxTranced
authored

Commits on Dec 16, 2019

One more HTTPS link
MaxTranced
authored