Adding instructions on how to update pre-compiled LVGL library.

Author: aentinger

README.md

@@ -15,6 +15,18 @@ This library allows you to control and interact with the 6 DOF Braccio++ robot a
 * [Help Center](https://support.arduino.cc/)
 * [Forum](https://forum.arduino.cc)
 
+### How-to-update precompiled `liblvgl`
+```bash
+git clone https://github.com/lvgl/lvgl
+git clone https://github.com/arduino-libraries/Arduino_Braccio_plusplus
+cd Arduino_Braccio_plusplus/extras
+mkdir build && cd build
+cmake ..
+make -j8
+cp liblvgl.a ../../src/cortex-m0plus/
+```
+**Note**: Copy all header files contained within `lvgl/src/*` to `Arduino_Braccio_plusplus/lib/lvgl/src`.
+
 ## :bug: Bugs & Issues
 
 If you want to report an issue with this library, you can submit it to the [issue tracker](https://github.com/arduino-libraries/Arduino_Braccio_plusplus/issues) of this repository. Remember to include as much detail as you can about your hardware set-up, code and steps for reproducing the issue. Make sure you're using an original Arduino board.