scripts: kernel-doc: Translate the "Output format selection" subsection of OPTIONS

Another step in the direction of a uniform POD documentation, which will
make users happier.

Options land at the end of the script, not to clutter the file top.

The default output format is corrected to rst. That's what it is now.

A POD delimiting comment is added to the script head, which improves
the script logical structure.

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/20220218181628.1411551-5-tomasz.warniello@gmail.com


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