kernel-doc/rst: do not output DOC: section titles for requested ones

If the user requests a specific DOC: section by name, do not output its
section title. In these cases, the surrounding context already has a
heading, and the DOC: section title is only used as an identifier and a
heading for clarity in the source file.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

scripts/kernel-doc

@@ -1764,7 +1764,9 @@ sub output_blockhead_rst(%) {
     my ($parameter, $section);
 
     foreach $section (@{$args{'sectionlist'}}) {
-	print "**$section**\n\n";
+	if ($output_selection != OUTPUT_INCLUDE) {
+	    print "**$section**\n\n";
+	}
 	output_highlight_rst($args{'sections'}{$section});
 	print "\n";
     }