Documentation: add entries to filesystems/00-INDEX for several untracked files

Signed-off-by: Denis Cheng <crquan@gmail.com>
Cc: Rob Landley <rob@landley.net>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>