README update

[Andrei Moraru]

Hi, I've been able to build and use CppFlow (only tested the QuickStart), but I'm not sure why there is a cd in the steps provided, so I had to skip it:

git clone [e-mail]:serizba/cppflow.git
cd cppflow/examples/load_model
mkdir build
cd build
cmake ..
make -j
make install

There is no CMakeLists.txt in there, so that was a bit confusing. Does this piece of info need an update or am I missing something?

Thanks and awesome project, btw!