pythonDocs: 3.7 -> 3.10

Also include texinfo docs for Python 3 (they aren't generated for
Python 2)

A few minor fixes had to be made to generate.sh as well.

pkgs/development/interpreters/python/cpython/docs/2.7-text.nix

@@ -2,13 +2,11 @@
 
 { stdenv, fetchurl, lib }:
 
-stdenv.mkDerivation rec {
-  pname = "python27-docs-text";
-  version = "2.7.16";
-
+stdenv.mkDerivation {
+  name = "python27-docs-text-2.7.18";
   src = fetchurl {
-    url = "http://docs.python.org/ftp/python/doc/${version}/python-${version}-docs-text.tar.bz2";
-    sha256 = "1da7swlykvc013684nywycinfz3v8dqkcmv0zj8p7l5lyi5mq03r";
+    url = http://www.python.org/ftp/python/doc/2.7.18/python-2.7.18-docs-text.tar.bz2;
+    sha256 = "1wj7mxs52kp5lmn5mvv574sygkfnk00kbz9ya9c03yfq5dd5nvy8";
   };
   installPhase = ''
     mkdir -p $out/share/doc/python27