doc: explain where pkgs comes from in writing-modules

The manual mentions how "[config and pkgs] are explained later". Added a link to where they are explained, and a hint pointing to the NIX_PATH variable.
2021-03-03 11:09:21 -05:00
parent 9004162c26
commit 5c99d24d1e
2 changed files with 8 additions and 4 deletions
@@ -74,7 +74,10 @@ linkend="sec-configuration-syntax"/>, we saw the following structure
   <callout arearefs='module-syntax-1'>
    <para>
     This line makes the current Nix expression a function. The variable
-     <varname>pkgs</varname> contains Nixpkgs, while <varname>config</varname>
+     <varname>pkgs</varname> contains Nixpkgs (by default, it takes the
+     <varname>nixpkgs</varname> entry of <envar>NIX_PATH</envar>, see the <link
+     xlink:href="https://nixos.org/manual/nix/stable/#sec-common-env">Nix
+     manual</link> for further details), while <varname>config</varname>
     contains the full system configuration. This line can be omitted if there
     is no reference to <varname>pkgs</varname> and <varname>config</varname>
     inside the module.