Add C# README.
Add C# README.

martincostello/electronicupdates,martincostello/electronicupdates,martincostello/electronicupdates,experiandataquality/electronicupdates,experiandataquality/electronicupdates,experiandataquality/electronicupdates,martincostello/electronicupdates,martincostello/electronicupdates,experiandataquality/electronicupdates,experiandataquality/electronicupdates