Expands on some of the function comments and add some of the
special syntaxes recognised by nixdoc.

Updates documentation comments with extra information for nixdoc[1]
compatibility.

Some documentation strings have additionally been reworded for
clarity.

"Faux types" are added where applicable, but some functions do things
that are not trivially representable in the type notation used so they
were ignored for this purpose.

[1]: https://github.com/tazjin/nixdoc

Updates documentation comments with extra information for nixdoc[1]
compatibility.

[1]: https://github.com/tazjin/nixdoc

Documents functions in `lib.debug` for docs generation with nixdoc.

Note that type signatures and clearer descriptions are still missing
on some of these functions, but this is good enough for a first run.

Documents functions in `lib.options` for docs generation with nixdoc.

The formatting change in the `mkOption` arguments is due to the way
`nixdoc` parses documentation comments on pattern arguments. It's not
ideal, but it works.

Update library function "docstrings" for nixdoc generation