Bug 25030: (QA follow-up) Add POD

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>

Koha/Filter/MARC/EmbedSeeFromHeadings.pm

@@ -77,6 +77,15 @@ sub _processrecord {
     return $record;
 }
 
+=head2 fields
+
+    my @fields = $filter->fields($record);
+
+Retrieve the fields that would be embedded if the record were processed by the filter.
+Used during Elasticsearch indexing to give special treatment to these field (i.e. don't
+include in facets, sorting, or suggestion fields)
+
+=cut
 sub fields {
     my ($self, $record) = @_;