nixos/pulseaudio: Fix description

nixos/modules/config/pulseaudio.nix

···
       support32Bit = mkOption {
         type = types.bool;
         default = false;
-        description = "no";
+        description = ''
+          Whether to include the 32-bit pulseaudio libraries in the systemn or not.
+          This is only useful on 64-bit systems and currently limited to x86_64-linux.
+        '';
       };
 
       configFile = mkOption {