docs: add comparison list to existing features in C#

[Odonno]

It may be interesting to add a grid comparison of features available in functional vs C# in the readme file. Here is a preview (not sure of the correct version) :

Functional features	C# equivalent	C# version	SuccincT equivalent	SuccincT version
Pattern matching
	is and switch / when	C# 7
Discriminated Unions		Planned for C# 8
Option		N/A
Partial applications		N/A

What do you think?

[DavidArno]

Is Option really planned for C# 8? Are you referring to nullable reference types?

It's an interesting idea. Not sure about pattern matching though. C# 7's pattern matching support is very limited. So I'd need to break down that down into types of patterns and detail what's covered, where.

Well worth considering though.

[Odonno]

@DavidArno I think you know it better than me. I updated the table so it looks like a corresponding table.

Tell me what is missing so we can complete the table and add it to the docs.