Add CrowCpp web framework for benchmark

[xerofenix]

I have seen the benchmark list it doesn't contain CrowCpp (https://crowcpp.org/master/) framework. It is a C++ web frameowork.

[joanhey]

This benchmark is open source, anybody is welcome to add a new framework !!

[xerofenix]

How can I add the framework? I think it is added by the maintainer after running benchmark stuffs.