All other functions are in the form of `*{c,C}heckpointBuild*`, so we
deprecate the `mkCheckpointedBuild` function in favor of `mkCheckpointBuild`.
Also address some inconsistencies in the docs: some `buildOutput` should
actually be `incrementalBuildArtifacts`.
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.
