zramctl: fix MEM-USED column description

zramctl: fix MEM-USED column description

The MEM-USED column was incorrectly documented as showing current
memory consumption. This is due to confusing naming in the kernel's
zram implementation:

- Kernel field "mem_used_total" (3rd in mm_stat) = current memory usage
- Kernel field "mem_used_max" (5th in mm_stat) = peak memory usage

zramctl maps these as:
- TOTAL column <= mem_used_total (current usage)
- MEM-USED column <= mem_used_max (peak usage)

The misleading "MEM-USED" name suggests current usage, but it actually
shows the peak memory usage (high water mark) since device creation
or last reset. This is tracked by the kernel's max_used_pages which
only increases when current usage exceeds the stored maximum.

Fixed description from:
"memory zram have been consumed to store compressed data" to
"peak memory usage to store compressed data".

Mise à jour de la traduction française.

(cherry picked from commit 616c88fb9565017c1a08c8869d2559b8d218c443)