Adds dt_overlay config instructions to README

Author: LivInAbsurdism

README.md

@@ -152,6 +152,23 @@ config :delux,
    }}
 ```
 
+For advanced configurations involving device tree overlays for GPIO-controlled LEDs, you can specify the overlays path and pins in the config.exs as follows:
+
+``` elixir
+config :delux, :dt_overlays,
+  overlays_path: "/data/gpio-led.dtbo",
+  pins: [
+    {"rgb-red0", 12},
+    {"rgb-green0", 16},
+    {"rgb-blue0", 21},
+    {"rgb-red1", 24},
+    {"rgb-green1", 25},
+    {"rgb-blue1", 1}
+  ]
+```
+
+This configuration is useful for specifying custom GPIO pins for LED indicators, allowing for more flexibility in custom hardware setups. This has only been tested on a rpi0 at this time.
+
 ## Use
 
 For sake of example, let's start the `Delux` GenServer the manual way by calling