document the disappearence of NoScript and HTTPSEverywhere icons from Tor Browser's toolbar

Users tend to (understandably) freak out when things are disappearing, so documenting this kind of changes, when planned, in the release notes would be really helpful for the Helpdesk.

in this case, a user that doesn’t know their way to about:addons or to customize the toolbar might think that NoScript is not installed, or not working,and that can be pretty confusing, especially since we are saying that 3.14 fixes a NoScript bug.

Related issues

• Related to #16727 (closed)

Original created by @goupille on 16746 (Redmine)