More elaborate README

[luzpaz]

• [ ] Screenshots (preferably animated gifs)
• [ ] Usage instructions.
• [ ] Logos for sverchok and Topologic

[wassimj]

We have limited resources. We are happy if other people can contribute. In the meantime, please check the youtube channel for instructional videos: https://www.youtube.com/playlist?list=PLomMn11gzPwTtQMZEWMU0zakg1YRdNuif There is a logo available for download at: https://topologic.app/press/