Documentation: move mandatory locking documentation to filesystems/

Shouldn't this mandatory-locking documentation be in the
Documentation/filesystems directory?

Give it a more descriptive name while we're at it, and update 00-INDEX
with a more inclusive description of Documentation/filesystems (which
has already talked about more than just individual filesystems).

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
diff --git a/Documentation/filesystems/00-INDEX b/Documentation/filesystems/00-INDEX
index 59db1bc..e801076 100644
--- a/Documentation/filesystems/00-INDEX
+++ b/Documentation/filesystems/00-INDEX
@@ -52,6 +52,8 @@
 	- info and mount options for the ISO 9660 (CDROM) filesystem.
 jfs.txt
 	- info and mount options for the JFS filesystem.
+mandatory-locking.txt
+	- info on the Linux implementation of Sys V mandatory file locking.
 ncpfs.txt
 	- info on Novell Netware(tm) filesystem using NCP protocol.
 ntfs.txt