make optional parameters in comment less ambiguious

Author: Arthur Cinader

src/Matrix.cc

@@ -2200,7 +2200,7 @@ NAN_METHOD(Matrix::TemplateMatches) {
 
 // @author ytham
 // Match Template filter
-// Usage: output = input.matchTemplate("templateFileString", ["method"], ["maskPath"]);
+// Usage: output = input.matchTemplate("templateFileString"[, "method"][, "maskPath"]);
 NAN_METHOD(Matrix::MatchTemplate) {
   Nan::HandleScope scope;