Added hackrf.app section

Update-firmware.md

@@ -61,6 +61,33 @@ Get the latest files from the [![GitHub release (latest by date)](https://img.sh
 >  - Don't use unbranded SD card.  
 > ![Screenshot_20240121_101958](https://github.com/portapack-mayhem/mayhem-firmware/assets/24917424/e14a2ef7-37bd-4a00-b19f-101235093e01)
 
+## Using the hackrf.app website
+- You need to use a browser compatible with Web USB Serial
+- The update using the website is only updating the firmware and external apps on the sdcard. If you want/need a full sdcard content update, please follow first the [Update SDCARD files](#update-sdcard-files) article, then update using the website
+
+### Procedure
+- Connect portapack using an USB cable with DATA enabled
+- Navigate to https://hackrf.app/
+- If never done, click on "Connect Device"
+
+![image](https://github.com/user-attachments/assets/8d1d333d-a6b4-4651-867a-03e06a849b70)
+
+- On the little pop up, select your Portapack, click 'Connect'
+
+![IMG_20241118_103143](https://github.com/user-attachments/assets/a08f5499-d0d2-404d-b442-246bc3de6757)
+
+- You should see "HackRF Connected" on top of the page, and the Live Screen will load the first screenshot
+- Scroll down to "Manage Firmware", and click it
+
+![image](https://github.com/user-attachments/assets/56a62da3-ce63-4eb6-83a2-00fe8069fcde)
+
+- Choose the firmware version to install (stable, nightly, or from a custom ppfw file)
+
+![image](https://github.com/user-attachments/assets/f761d1e5-65c5-4869-a0ad-15cb97626c4d)
+
+- Wait for the file to be uploaded, and for your device to automatically reboot
+- Done !
+
 # Troubleshooting
 
 - Please check [this guide](Update-firmware-troubleshooting)