kwm: add key for lock

kwm/.config/kwm/config.zon

@@ -1024,6 +1024,17 @@
                     },
                 },
             },
+            .{
+                .keysym = "l",
+                .modifiers = .{ .mod4 = true, .shift = true },
+                .event = .{
+                    .click = .{
+                        .pressed = .{
+                                .spawn = .{ .argv = .{ "waylock" } },
+                        },
+                    },
+                },
+            },
         },
 
         // list of pointer bindings