Describe the enhancement requested

The documentation for Arrow Format could be improved with with a not too technical content that would serve as an introductory to the format spec. It would be worth having a separate page that would include:

• content about the idea of the columnar format
• different physical layouts explained together with diagrams of example type in comparison to the physical layout
• main Arrow terminology (record batch, array, etc.)
• Arrow C Data interface

Component(s)

Documentation, Format