docs: Invalid instructions for flashing oniro to Raspberry 4

The module affected

Raspberry 4

What is the action to reproduce the bug?

Follow the instructions for flashing to raspberry.

What is the result you see?

At the flashing to SD card section you should encounter an error:

bmaptool: ERROR: cannot open image:
cannot open URL 'oniro-image-base-raspberrypi4-64.wic.bz2': unknown url type: 'oniro-image-base-raspberrypi4-64.wic.bz2'

What is the result you expect?

Flash image to SD card

Frequency?

Always

Tested version

build-oniro-linux-raspberrypi4-64 with oniro-image-base and blueprint-energy-gateway-image

Do you know any workaround of this issue?

Use oniro-image-base-raspberrypi4-64.wic.gz insted of oniro-image-base-raspberrypi4-64.wic.bz2

Do you have a fix for this issue?

!212 (merged)