Adds another signs and songs match

src/main/java/net/knarcraft/ffmpegconverter/streams/SubtitleStream.java

@@ -105,7 +105,8 @@ public class SubtitleStream extends AbstractStream implements StreamObject {
                 !titleLowercase.matches(".*forced.*") &&
                 !titleLowercase.matches(".*s&s.*") &&
                 !titleLowercase.matches("signs?") &&
-                !titleLowercase.matches("songs?");
+                !titleLowercase.matches("songs?") &&
+                !titleLowercase.contains("signs only");
     }
 
 }