[Keymap] Correction for DE_Simple keymap readme (#5870)

Replaced erroneous second QWERTZ keymap with diagramm for 'Lower'
layer.

keyboards/lets_split/keymaps/DE_simple/readme.md

@@ -21,15 +21,15 @@ Layout
     `-----------------------------------------------------------------------------------'
     
     
-    Qwerty
+    Lower
     ,-----------------------------------------------------------------------------------.
-    | Esc  |   Q  |   W  |   E  |   R  |   T  |   Z  |   U  |   I  |   O  |   P  | Bksp |
+    |   °  |   !  |   "  |   §  |   $  |   %  |   &  |   /  |   (  |   )  |   =  | Bksp |
     |------+------+------+------+------+-------------+------+------+------+------+------|
-    | Tab  |   A  |   S  |   D  |   F  |   G  |   H  |   J  |   K  |   L  |   +  |  #   |
+    | Del  |  F1  |  F2  |  F3  |  F4  |  F5  |  F6  |   @  |   €  |   ü  |   ?  |  ´   |
     |------+------+------+------+------+------|------+------+------+------+------+------|
-    | Shift|   Y  |   X  |   C  |   V  |   B  |   N  |   M  |   ,  |   .  |   -  |Enter |
+    | Shift|  F7  |  F8  |  F9  |  F10 |  F11 |  F12 |   |  |   ö  |   ä  |      |Enter |
     |------+------+------+------+------+------+------+------+------+------+------+------|
-    | Ctrl | Alt  | AltGr| GUI  |Lower |Space |Space |Raise | Left | Down |  Up  |Right |
+    |      |      |      |      |      |             |      | Next | Vol- | Vol+ | Play |
     `-----------------------------------------------------------------------------------'