Merge branch 'vfs' into docs-next

Work from Tobin Harding:

	Here is an updated version of the VFS doc conversion.  This series
	in no way represents a final point for the VFS documentation rather
	it is a small step towards getting VFS docs updated.  This series
	does not update the content of vfs.txt, only does formatting.

Documentation/filesystems/index.rst

@@ -16,6 +16,7 @@ algorithms work.
 .. toctree::
    :maxdepth: 2
 
+   vfs
    path-lookup.rst
    api-summary
    splice