PM / hibernate: Documentation: fix image_size default value

This commit updates the default value of /sys/power/image_size in
the documentation.

Since ac5c24ec1e983313ef0015258fba6f630e54e7cn the `image_size' value is
set to about 2/5 of RAM, according to kernel/power/snapshot.c:

	image_size = ((totalram_pages * 2) / 5) * PAGE_SIZE;

but this change was not reflected everywhere in the documentation.

Signed-off-by: Vladimir D. Seleznev <vseleznv@altlinux.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Documentation/ABI/testing/sysfs-power

@@ -99,7 +99,7 @@ Description:
 		this file, the suspend image will be as small as possible.
 
 		Reading from this file will display the current image size
-		limit, which is set to 500 MB by default.
+		limit, which is set to around 2/5 of available RAM by default.
 
 What:		/sys/power/pm_trace
 Date:		August 2006

Documentation/power/swsusp.txt

@@ -56,7 +56,7 @@ If you want to limit the suspend image size to N bytes, do
 
 echo N > /sys/power/image_size
 
-before suspend (it is limited to 500 MB by default).
+before suspend (it is limited to around 2/5 of available RAM by default).
 
 . The resume process checks for the presence of the resume device,
 if found, it then checks the contents for the hibernation image signature.