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

Aim: unified POD, user more satisfied, script better structured

A subsection "reStructuredText only" is added for -enable-lineno.

Other notes:
- paragraphing 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/20220218181628.1411551-8-tomasz.warniello@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

scripts/kernel-doc

@@ -83,14 +83,6 @@ sub usage {
     my $message = <<"EOF";
 Usage: $0 [OPTION ...] FILE ...
 
-Output selection modifiers:
-  -no-doc-sections	Do not output DOC: sections.
-  -enable-lineno        Enable output of #define LINENO lines. Only works with
-                        reStructuredText format.
-  -export-file FILE     Specify an additional FILE in which to look for
-                        EXPORT_SYMBOL() and EXPORT_SYMBOL_GPL(). To be used with
-                        -export or -internal. May be specified multiple times.
-
 Other parameters:
   -v			Verbose output, more warnings and other information.
   -h			Print this help.
@@ -2607,4 +2599,33 @@ May be specified multiple times.
 
 =back
 
+=head2 Output selection modifiers:
+
+=over 8
+
+=item -no-doc-sections
+
+Do not output DOC: sections.
+
+=item -export-file FILE
+
+Specify an additional FILE in which to look for EXPORT_SYMBOL() and
+EXPORT_SYMBOL_GPL().
+
+To be used with -export or -internal.
+
+May be specified multiple times.
+
+=back
+
+=head3 reStructuredText only
+
+=over 8
+
+=item -enable-lineno
+
+Enable output of #define LINENO lines.
+
+=back
+
 =cut