Documentation: zram: various fixes in zram.rst

Fix various items in zram.rst:
- typos/spellos
- punctuation
- grammar
- shell syntax
- indentation
- sysfs file names

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Link: https://lore.kernel.org/r/77000e12-677a-62f6-9f78-343be5bd6630@infradead.org


Signed-off-by: Jonathan Corbet <corbet@lwn.net>