Documentation: update hugetlb information

The hugetlb documentation has gotten a bit out of sync with the current code.
Updated the sysctl file to refer to Documentation/vm/hugetlbpage.txt.  Update
that file to contain the current state of affairs (with the newer named sysctl
in place).

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Acked-by: Adam Litke <agl@us.ibm.com>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/sysctl/vm.txt

@@ -34,6 +34,8 @@ Currently, these files are in /proc/sys/vm:
 - oom_kill_allocating_task
 - mmap_min_address
 - numa_zonelist_order
+- nr_hugepages
+- nr_overcommit_hugepages
 
 ==============================================================
 
@@ -305,3 +307,20 @@ will select "node" order in following case.
 
 Otherwise, "zone" order will be selected. Default order is recommended unless
 this is causing problems for your system/application.
+
+==============================================================
+
+nr_hugepages
+
+Change the minimum size of the hugepage pool.
+
+See Documentation/vm/hugetlbpage.txt
+
+==============================================================
+
+nr_overcommit_hugepages
+
+Change the maximum size of the hugepage pool. The maximum is
+nr_hugepages + nr_overcommit_hugepages.
+
+See Documentation/vm/hugetlbpage.txt