Try different build strategy

examples/arduino-signed-ota/README.md

@@ -0,0 +1,29 @@
+How to build PlatformIO based project
+=====================================
+
+1. [Install PlatformIO Core](https://docs.platformio.org/page/core.html)
+2. Download [development platform with examples](https://github.com/platformio/platform-raspberrypi/archive/develop.zip)
+3. Extract ZIP archive
+4. Run these commands:
+
+```shell
+# Change directory to example
+$ cd platform-raspberrypi/examples/arduino-blink
+
+# Build project
+$ pio run
+
+# Upload firmware
+$ pio run --target upload
+
+# Clean build files
+$ pio run --target clean
+```
+
+## Notes
+
+For Raspberry Pi Pico devices, two Arduino cores exist:
+* https://github.com/arduino/ArduinoCore-mbed
+* https://github.com/earlephilhower/arduino-pico
+
+This examples showcases how to use both of these cores in the `platformio.ini`.