docs: stable-kernel-rules: move text around to improve flow

Move the short description about when to use which of the submission
options to the top of the section, as it currently sits somewhat odd in
the middle between option 3 and examples of option 1.

Also move the examples of Option 1 into the section describing it (which
in the diff looks like option 2 and 3 are moving down).

No text changes, just moving it around.

CC: Greg KH <gregkh@linuxfoundation.org>
CC: Sasha Levin <sashal@kernel.org>
CC: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info>
Link: https://lore.kernel.org/r/16f2377ee40dd7dfa146727fcbe7d1ebccf5b5be.1691219455.git.linux@leemhuis.info


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>