python3.pkgs.psycopg2: build offline documentation

pkgs/development/python-modules/psycopg2/default.nix

@@ -6,11 +6,14 @@
 , fetchPypi
 , postgresql
 , openssl
+, sphinxHook
+, sphinx-better-theme
 }:
 
 buildPythonPackage rec {
   pname = "psycopg2";
   version = "2.9.3";
+  outputs = [ "out" "doc" ];
 
   # Extension modules don't work well with PyPy. Use psycopg2cffi instead.
   # c.f. https://github.com/NixOS/nixpkgs/pull/104151#issuecomment-729750892
@@ -23,6 +26,8 @@ buildPythonPackage rec {
 
   nativeBuildInputs = [
     postgresql
+    sphinxHook
+    sphinx-better-theme
   ];
 
   buildInputs = lib.optionals stdenv.isDarwin [
@@ -32,6 +37,8 @@ buildPythonPackage rec {
   # requires setting up a postgresql database
   doCheck = false;
 
+  sphinxRoot = "doc/src";
+
   meta = with lib; {
     description = "PostgreSQL database adapter for the Python programming language";
     homepage = "https://www.psycopg.org";