Add method to return Span<bool> for coils, etc

[the-programmer]

Via https://stackoverflow.com/a/61367679 I found that C# has (quite a while actually) the bitarray class.

If you update the documentation so we get

var coils = client.ReadCoils(1, 0x8000, 255);
var bits = new BitArray(coils.ToArray());

The coils array will be converted to an bitarray by C#

[Apollo3zehn]

Thank you, I will consider it for the next update!