Replace specific hostname with generic placeholder in sha256sum example output

[Copilot]

The example output block in T480s-maximized.md used [user@h4ckb0x ~]$ as the shell prompt, which is distracting and machine-specific in a user-facing guide.

Change

• Replaced [user@h4ckb0x ~]$ with [user@host ~]$ on both prompt lines in the sha256sum example output block:

-[user@h4ckb0x ~]$ sha256sum t480s_original_bios.bin
+[user@host ~]$ sha256sum t480s_original_bios.bin
 54d58fdf217f41d4385576bb74f45f20de233d1a9d9ea2d6f1543b86111e1062  t480s_original_bios.bin
-[user@h4ckb0x ~]$ sha256sum t480s_original_bios_1.bin
+[user@host ~]$ sha256sum t480s_original_bios_1.bin
 54d58fdf217f41d4385576bb74f45f20de233d1a9d9ea2d6f1543b86111e1062  t480s_original_bios_1.bin

[tlaurion]

as justified https://matrix.to/#/!eMLMv62wAMCW1V-ufL_bJ_JDngDhrpSOSEQBLzX8aTg/$H-hRieYDKgmqwbaYmxztFPXMdbNi4wsd-ZjqtHoR0bg?via=matrix.org&via=tchncs.de&via=unredacted.org