Segmentation Tutorial (#9521)

* Added a tutorial notebook for segmentation.

* Updated header for segmentation tutorial and included other YOLOv5 sponsor sections.

* Updated segmentation tutorial to match main object detection tutorial.

* Update tutorial.ipynb

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: Ayush Chaurasia <ayush.chaurarsia@gmail.com>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>