doc: move vm/00-INDEX to Documentation/vm

Looks like the 00-INDEX file lost its parent directory in -rc6-mm1.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/vm/00-INDEX b/Documentation/vm/00-INDEX
similarity index 100%
rename from vm/00-INDEX
rename to Documentation/vm/00-INDEX