The expansion into absolute paths caused the filter to reject all the
files in some unusual circumstances (we think it's due to use of a
chroot store). This works reliably no matter where nixpkgs is located.
Makes the build independency of the default.nix and update.sh file by
explicitly specifying the files that are needed in the result
This allows changing those files without causing a rebuild
- Rectifies diverging CSS by combining
nixos/nixpkgs docs CSS
- Moves our custom Highlight.js loader in to
the hljs package
- Switches the nixos docs to use SVG
callouts too
