fix .gitignore not tracking existing folders (#5946)

* fix .gitignore not tracking existing folders

fix .gitignore so that the files that are in the repository are actually being tracked.

Everything in the data/ folder is ignored, which also means the subdirectories are ignored. Fix so that the subdirectories and their contents are still tracked.

* Remove data/trainings

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

.gitignore

 storage.googleapis.com
 runs/*
 data/*
-!data/hyps/*
+data/images/*
+!data/*.yaml
+!data/hyps
+!data/scripts
+!data/images
 !data/images/zidane.jpg
 !data/images/bus.jpg
 !data/*.sh