Example on how to set USE_CUSTOM_H for Arduino IDE (#484)

code/espurna/config/all.h

@@ -1,13 +1,24 @@
 /*
+
     If you want to modify the stock configuration but you don't want to touch
-    the repo files you can either define USE_CUSTOM_H or remove the
-	"#ifdef USE_CUSTOM_H" & "#endif" lines and add a "custom.h"
-    file to this same folder.
+    the repo files you can define USE_CUSTOM_H in your build settings.
+
+    Arduino IDE:
+    define it in your boards.txt for the board of your choice.
+    For instance, for the "Generic ESP8266 Module" with prefix "generic" just add:
+
+        generic.build.extra_flags=-DESP8266 -DUSE_CUSTOM_H
+
+    PlatformIO:
+    add the setting to your environment or just define global PLATFORMIO_BUILD_FLAGS
+
+        export PLATFORMIO_BUILD_FLAGS="'-DUSE_CUSTOM_H'"
+
     Check https://github.com/xoseperez/espurna/issues/104
     for an example on how to use this file.
-	(Define USE_CUSTOM_H on commandline for platformio:
-	export PLATFORMIO_BUILD_FLAGS="'-DUSE_CUSTOM_H'" )
+
 */
+
 #ifdef USE_CUSTOM_H
 #include "custom.h"
 #endif