* Note on how to use shadowSetup with buildLayeredImage
* Update doc/build-helpers/images/dockertools.section.md
---------
Co-authored-by: Silvan Mosberger <github@infinisil.com>
The mkBinaryCache section now follows the convention of using one
line per sentence, as well as using admonitions for notes and
examples.
The example syntax was updated to define a fully-working nix package.
The following changes are made:
- Document how `wrapType2` and `wrapType1` are the same thing.
- Expand on how `wrapType2` works and additional arguments it uses.
- Document `extract` and show how it's used in combination with
`wrapType2`.
- Provide full working examples using the new admonition syntax.
