07_vision.core: create docments

[warner-benjamin]

Add docments to 07_vision.core.

See the style guide and contribution guide for more details (links will be added when created).

This requires a moderate to advanced familiarity with fastai, specifically fastai's Datablock pipelines. This notebook defines reading standard image data types and basic transforms.

Docments progress:

• [ ] Helpers
• [ ] Basic types
• [ ] Images
• [ ] Segmentation masks
• [ ] Points
• [ ] Bounding boxes
• [ ] Basic Transforms