Staging: zram: Rename ramzswap to zram in documentation

Related changes:
 - Included example to show usage as generic
(non-swap) disk with ext4 filesystem.
 - Renamed rzscontrol to zramconfig to match
with new device naming.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>