package.nix previously needed this callPackage'd externally, which
didn't make a lot of sense to us since this is an internal dependency.
Thus we changed it to make it more self contained.
Change-Id: I4935bc0bc80e1a132bc9b1519e917791da95037c
For a long time `nix repl` has supported displaying documentation set on
builtins, however, it has long been convention to use Markdown comments
on Nix functions themselves for documentation. This exposes that
information to `nix repl` users in a nice and formatted way.
NixOS/rfcs#145 doc-comments are primarily what this feature is intended
to consume, however, support for lambda documentation in the repl is
experimental. We do our best effort to support the RFC here.
These changes are based on [the nix-doc library](https://github.com/lf-/nix-doc) and
are licensed under the terms described in the relevant source files.
Change-Id: Ic6fe947d39a22540705d890737e336c4720b0a22
