Documentation about RaGAN and perpetual pre-training

[CristianCerasuoloo]

Pull Request

Description

Documentation update

Type of change

Please delete options that are not relevant.

• Documentation update

How Has This Been Tested?

No tests were needed

Checklist:

• [X ] I have performed a self-review of my own code
• [ X] I have commented my code, particularly in hard-to-understand areas
• [ X] I have made corresponding changes to the documentation
• [ X] My changes generate no new warnings
• I have added tests that prove that my feature works
• New and existing unit tests pass locally with my changes
• [ X] Any dependent changes have been merged and published in downstream modules