zram: tweak writeback config help

Writeback is for incompressible and idle zram pages.

Link: https://lkml.kernel.org/r/20231115024223.4133148-2-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Dmytro Maluka <dmaluka@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/block/zram/Kconfig

@@ -59,8 +59,8 @@ config ZRAM_WRITEBACK
        bool "Write back incompressible or idle page to backing device"
        depends on ZRAM
        help
-	 With incompressible page, there is no memory saving to keep it
-	 in memory. Instead, write it out to backing device.
+	 This lets zram entries (incompressible or idle pages) be written
+	 back to a backing device, helping save memory.
 	 For this feature, admin should set up backing device via
 	 /sys/block/zramX/backing_dev.