Documentation: ublk: Separate UBLK_F_AUTO_BUF_REG fallback behavior sublists

Documentation: ublk: Separate UBLK_F_AUTO_BUF_REG fallback behavior sublists

Stephen Rothwell reports htmldocs warning on ublk docs:

Documentation/block/ublk.rst:414: ERROR: Unexpected indentation. [docutils]

Fix the warning by separating sublists of auto buffer registration
fallback behavior from their appropriate parent list item.

Fixes: ff20c516485e ("ublk: document auto buffer registration(UBLK_F_AUTO_BUF_REG)")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/linux-next/20250612132638.193de386@canb.auug.org.au/
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/r/20250613023857.15971-1-bagasdotme@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>