Adding benchmarks to the documentation

[HakamFostok]

First of all, Thank you very very much @mgravell for your hugely-appreciated efforts. .NET would not be the same without you. This library is very great and very important, and I can not stop introducing my friends and colleagues to it.

I would just suggest adding benchmarks to the documentation to show how important this library is. It will be the easiest way for people to understand its importance by seeing how faster and less memory this approach provides.

Thank you a lot again