GumGum: updates doc to include iriscat field (#2376)
GumGum: updates doc to include iriscat field (#2376)

* specifies us privacy is supported

* adds video support to gumgum md

* adds support for tcf 2

* adds new bid param to gumgum.md

* updates gumgum doc
prebid/prebid.github.io,prebid/prebid.github.io,prebid/prebid.github.io