A CFP (Call for proposal) page on DNF website

Currently the DNF website has a speaker list. If we build a page with CFPs, it would be easy to match speakers with group organizers. (On similar patterns of MVP CFPs in Microsoft MVP channels)

Originally from @codehippie1 [Membership Committee Issue](https://github.com/dotnet-foundation/wg-membership/issues/105)