- Move design document for batch instance creation into it
- Sort list of hidden files in index.rst

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

It contains links to the two implemented designs. The detailed documents
are removed from the visible table of contents to not show up on their
own.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>