chawan: fix example for settings (#7210)

as per cha-config, keybindings should be under section `page` and not `pager`.

Also replaced the line with an example from man page because the current one wasn't working properly

modules/programs/chawan.nix

@@ -30,7 +30,7 @@ in
             images = true;
             autofocus = true;
           };
-          pager."C-k" = "() => pager.load('https://duckduckgo.com/?=')";
+          page."C-k" = "() => pager.load('ddg:')";
         }
       '';
     };