Modified works are derivative works, they are under the scope
of 106 (2) (while they are under 106 (1) as well). I assume
the intention here was to clarify they're the easy case of derivative
works? That seems important and correct.

Proposed a few tweaks to express this idea without implying that modified
works are not derivative works.

Signed-off-by: enyst <engel.nyst@gmail.com>