Add note to the documentation

Author: lucasssvaz

README.md

@@ -34,6 +34,7 @@ To use it, follow these steps:
 5. The script will show the compilation output in a new screen. Note that the compilation process can take many hours, depending on the number of libraries selected and the options chosen.
 
 6. If the compilation is successful and the option to copy the libraries to the Arduino Core folder is enabled, it will already be available for use in the Arduino IDE. Otherwise, you can find the compiled libraries in the `esp32-arduino-libs` folder alongside this repository.
+  - Note that the copy operation doesn't currently support the core downloaded from the Arduino IDE Boards Manager, only the manual installation from the [`arduino-esp32`](https://github.com/espressif/arduino-esp32) repository.
 
 ### Documentation