Things missing from Data Book

[galenlynch]

Just creating an issue to track the issues brought up on slack:

• [ ] Primer on the cortical microcircuit and cell types
• [x] Background on ISI (resolved by #17 and #18)
• [x] Background on calcium imaging, and two-photon excitation calcium imaging (resolved by #19)
• [x] Make cheat sheets more prominent (addressed by 4cc17133f6251eb67dc9971c25009d2d5cbbe9a0)
• [x] Add Yoni's head frame material (#20)
• [ ] Explain differences & similarities between VBO and VBN datasets

• [ ] Show how to view images from the Visual Coding Neuropixels dataset

  Feel free to add more

[galenlynch]

I think @alakunina is working on a primer on cortical microcircuit and cell types