Clarify that for now, only classic projects are supported for backporting.
Clarify that for now, only classic projects are supported for backporting.

ejgallego/coq,SkySkimmer/coq,coq/coq,coq/coq,ejgallego/coq,ejgallego/coq,SkySkimmer/coq,coq/coq,coq/coq,ejgallego/coq,SkySkimmer/coq,SkySkimmer/coq