docs/vm: ksm: split userspace interface to admin-guide/mm/ksm.rst

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/admin-guide/mm/index.rst b/Documentation/admin-guide/mm/index.rst
index 6c8b554..ad28644 100644
--- a/Documentation/admin-guide/mm/index.rst
+++ b/Documentation/admin-guide/mm/index.rst
@@ -23,6 +23,7 @@
 
    hugetlbpage
    idle_page_tracking
+   ksm
    pagemap
    soft-dirty
    userfaultfd