Fix formatting in BeagleBone Blue firmware flashing page (flashing-firmware.rst)
requested to merge SomeInterestingUserName/docs.beagleboard.io:SomeInterestingUserName-main-patch-46562 into main
I noticed the Linux/macOS instructions for flashing the BeagleBone Blue (https://docs.beagleboard.org/latest/boards/beaglebone/blue/flashing-firmware.html) has some formatting issues and wasn't displaying correctly. I didn't make any content changes, just fixed the markdown to be consistent with the Windows instructions in the preceding section.