scripts: kernel-doc: Refresh the copyright lines

I wanted to clean up these lines, but in the end decided not to touch
the old ones and just add my own about POD. I'll leave the cleanup
for lawyers.

Signed-off-by: Tomasz Warniełło <tomasz.warniello@gmail.com>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Disliked-by: Akira Yokosawa <akiyks@gmail.com>
Link: https://lore.kernel.org/r/20220218181628.1411551-12-tomasz.warniello@gmail.com


Signed-off-by: Jonathan Corbet <corbet@lwn.net>