Renamed JSON source of Ergodox Swiss German

- Renamed the JSON source files for the layout description of
    the Ergodox Swiss German keymap

keyboards/ergodox/keymaps/swissgerman/readme.md

@@ -4,7 +4,7 @@ Swiss German keyboard layout based on the Ergodox EZ default layout.
 
 Keyboard diagrams created with the [keyboard layout editor](http://www.keyboard-layout-editor.com).
 
-Diagram sources: [default layer](keyboard-layout.json), [layer 2 & 3](keyboard-layout_2_3.json)
+Diagram sources: [default layer](keyboard-layout.json), [layer 1 & 2](keyboard-layout_1_2.json)
 
 ![Layout Layer 0](keyboard-layout.png)
 ![Layout Layer 1&2](keyboard-layout_1_2.png)