Update README section about using setup.py

[PokhodenkoSA]

Section: https://github.com/IntelPython/dpctl#build-and-install-with-setuptools
It should contain which packages should be installed:

• cmake
• ninja - for Windows only
• cython
• numpy - optionally?

It is necessary to verified this list on Linux and Widows.

[oleksandr-pavlyk]

cython, cmake and numpy are required dependencies on all platforms. ninja is required on Windows only.