"Security Work for 20.1" doc

[Amruta-Ranade]

Go through the "Security Work for 20.1" doc and make sure all the things are documented for 20.1
https://docs.google.com/document/d/1zljr8VkP1wnf-kcRp7nL_WYCqVzHdmWdU3Q3KqWX-5Y/

[Amruta-Ranade]

Discussion with Raphael: https://docs.google.com/document/d/1vlV9dS2YutvS2_oLyp3we4GGyekxTBsDaLj4Ca3gAAA

[Amruta-Ranade]

Addressed most issues in #7104 and #7061 and created separate issues for remaining work.