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

Aim: unified POD, user more happy

This section is renamed to "Output format modifiers" to make it simple.

To make it even more simple, a subsection is added:
"reStructuredText only".

Other notes:
- paragraphing correction
- article correction
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/20220218181628.1411551-6-tomasz.warniello@gmail.comSigned-off-by: Jonathan Corbet <corbet@lwn.net>

scripts/kernel-doc

@@ -83,13 +83,6 @@ sub usage {
     my $message = <<"EOF";
 Usage: $0 [OPTION ...] FILE ...
 
-Output format selection modifier (affects only ReST output):
-
-  -sphinx-version	Use the ReST C domain dialect compatible with an
-			specific Sphinx Version.
-			If not specified, kernel-doc will auto-detect using
-			the sphinx-build version found on PATH.
-
 Output selection (mutually exclusive):
   -export		Only output documentation for symbols that have been
 			exported using EXPORT_SYMBOL() or EXPORT_SYMBOL_GPL()
@@ -2583,4 +2576,19 @@ Do not output documentation, only warnings.
 
 =back
 
+=head2 Output format modifiers
+
+=head3 reStructuredText only
+
+=over 8
+
+=item -sphinx-version VERSION
+
+Use the ReST C domain dialect compatible with a specific Sphinx Version.
+
+If not specified, kernel-doc will auto-detect using the sphinx-build version
+found on PATH.
+
+=back
+
 =cut