Documentation/: it's -> its where appropriate

Fix obvious cases of "it's" being used when "its" was meant.

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 3a6aecd..6cab1f2 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -263,7 +263,7 @@
 
 4.2 Task migration
 
-When a task migrates from one cgroup to another, it's charge is not
+When a task migrates from one cgroup to another, its charge is not
 carried forward by default. The pages allocated from the original cgroup still
 remain charged to it, the charge is dropped when the page is freed or
 reclaimed.