Confirm merge from FromPublicMasterBranch to master to sync with https://github.com/MicrosoftDocs/cpp-docs (branch master) (MicrosoftDocs#468)

* Update compiler-warnings-that-are-off-by-default.md

Added missing link. C4682

* describe the variadic template args now used, fill in missing parts

This page was documenting the pre-Variadic template arg version of this function, was missing several important things so I've updated it

* pr feedback from Raymond

thank you Raymond

* FtmBase is a class, not a member of RuntimeClassType

* fixed pre-existing typo

Author: openpublishbuild