Create FUNDING.yaml (#1743)

This should set up a "Sponsor" button on the repository to allow users and organizations to help with the development of YOLOv5 with financial contributions! 

I feel like 10 sponsors could really help fund Ultralytics' caffeine ☕ addiction and get YOLOv5 🚀 developed and deployed faster than ever! 😃

.github/FUNDING.yml

+# These are supported funding model platforms
+
+github: glenn-jocher
+patreon: ultralytics
+open_collective: ultralytics