update-training-scripts

[david-thrower]

Add to the repo:

1. The remedial pretrain script.
2. The instruct fine tune scipt.
3. documentation of the 3 stage curriculum, rationale, ... links to the best instruct fine tune model and recommended remedial - pretrained base model, examples of chat sessions from the 512 seq len instruct model.

Instruct fine tuning:

instruct_fine_tuning_script_rough_draft.py

Remedial pre-train:

remedial-pretrain.py