Add docs to dataset template generator

[lgvaz]

🚀 Feature

Automatically create/update the necessary documentation files when using the generator.

autogen.py
Automate the readme creation, currently we have to copy each file individually:

    # Copy Birds README
    shutil.copyfile(icedata_dir / "icedata/datasets/birds/README.md", dest_dir / "birds.md")

    # Copy COCO README
    shutil.copyfile(icedata_dir / "icedata/datasets/coco/README.md", dest_dir / "coco.md")

mkdocs.yml
Update the Datasets section:

  - Datasets:
    - Birds: birds.md
    - COCO: coco.md