Training README should move to `training` folder

[iingram]

The training portion of the README is very long and mainly of interest to folks who want to do training and those folks are not the only users of camml. Thus, this text should move to a more appropriate place perhaps as a README in the training folder or as a training.md markdown document at the repo top level and this separate document should only be referenced (maybe linked) from the main README.

[iingram]

While we are at it, probably should look at separating the YOLOv8 workflow README from the TFLite EfficientDet workflow README