A recent documentation conversion renamed this file but forgot
to update the links.

Fixes: af96c1e3 ("docs: filesystems: vfs: Convert vfs.txt to RST")
Signed-off-by: NMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>