[NWD] Adds CONTRIBUTING.md file Change-Id: I04fc8f419e6593461152fa0c3258cab12c36aaee
AppSheet fork of EPPlus
To compile this fork, run: dotnet pack EPPlus/EPPlusSDK.csproj -c Release
Then, copy the .nupkg file: EPPlus/bin/Release/Appsheet.EPPlus.1.0.0.nupkg -> jeenee/lib/nuget