docs: submitting-patches: clarify difference between Acked-by and Reviewed-by

Newcomers to the kernel need to learn the different tags that are
used in commit messages and when to apply them. Acked-by is sometimes
misunderstood, since the documentation did not really clarify (up to
the previous commit) when it should be used, especially compared to
Reviewed-by.

The previous commit already clarified who the usual providers of Acked-by
tags are, with examples. Thus provide a clarification paragraph for
the comparison with Reviewed-by, and give a couple examples reusing the
cases given above, in the previous commit.

Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250112152946.761150-3-ojeda@kernel.org