gnupg*: Improve the meta set

And use version from gnupg21 for gnupg1compat.

pkgs/tools/security/gnupg/1.nix

@@ -12,10 +12,21 @@ stdenv.mkDerivation rec {
 
   doCheck = true;
 
-  meta = {
-    description = "Free implementation of the OpenPGP standard for encrypting and signing data";
-    homepage = http://www.gnupg.org/;
-    license = stdenv.lib.licenses.gpl3Plus;
-    platforms = stdenv.lib.platforms.gnu; # arbitrary choice
+  meta = with stdenv.lib; {
+    homepage = "https://gnupg.org";
+    description = "Classic (1.4) release of the GNU Privacy Guard, a GPL OpenPGP implementation";
+    license = licenses.gpl3Plus;
+    longDescription = ''
+      The GNU Privacy Guard is the GNU project's complete and free
+      implementation of the OpenPGP standard as defined by RFC4880.  GnuPG
+      "classic" (1.4) is the old standalone version which is most suitable for
+      older or embedded platforms.  GnuPG allows to encrypt and sign your data
+      and communication, features a versatile key management system as well as
+      access modules for all kind of public key directories.  GnuPG, also known
+      as GPG, is a command line tool with features for easy integration with
+      other applications.  A wealth of frontend applications and libraries are
+      available.
+    '';
+    platforms = platforms.gnu; # arbitrary choice
   };
 }