datasheet: add texplained chip scans

[mattvenn]

I guess the best place will be after the renders.

Should be intro'd with some text like:

Thanks to Texplained for chip decap and scans.
Then each image described:

Image shows top metal 5. This layer is mostly used for power distribution.
Image shows substrate. This is done after all material is removed from the substrate.

[urish]

To add them after the renders, simply edit docs/chip_map.md in the respective shuttle repo, e.g. https://github.com/TinyTapeout/tinytapeout-06/blob/main/docs/chip_map.md.

The images themselves can be added to docs/images/ in the respective shuttle's repo.