Updated CONTRIBUTING.md to reflect the use of NuGet packages.
Updated CONTRIBUTING.md to reflect the use of NuGet packages.

adamchester/AutoFixture,StevenJiang2015/AutoFixture,mrinaldi/AutoFixture,zvirja/AutoFixture,dcastro/AutoFixture,dlongest/AutoFixture,sergeyshushlyapin/AutoFixture,StevenJiang2015/AutoFixture,dcastro/AutoFixture,sbrockway/AutoFixture,mrinaldi/AutoFixture,sbrockway/AutoFixture,sean-gilliam/AutoFixture,hackle/AutoFixture,adamchester/AutoFixture,olegsych/AutoFixture,olegsych/AutoFixture,Pvlerick/AutoFixture,hackle/AutoFixture,dlongest/AutoFixture,amarant/AutoFixture,amarant/AutoFixture,sergeyshushlyapin/AutoFixture,AutoFixture/AutoFixture,yuva2achieve/AutoFixture,yuva2achieve/AutoFixture