add comments

vtest/source/app.d

@@ -132,7 +132,7 @@ void hello(HTTPServerRequest req, HTTPServerResponse res){
 
 
 /*
-void test_pg_conn_driver(){
+void test_pg_conn_driver(){  // https://github.com/denizzzka/vibe.d.db.postgresql/blob/master/example/example.d#L13
   client.pickConnection( (scope conn){
     immutable result = conn.execStatement(
       "SELECT 123 as first_num, 567 as second_num, 'abc'::text as third_text " ~
@@ -160,9 +160,9 @@ void test_pg_conn_driver_queries(){
   
   client.pickConnection( (scope conn){
     conn.prepareStatement("get_city_by_id", "SELECT id, name, population FROM test WHERE id = $1"); // get_city_by_id
-    QueryParams params;
+    QueryParams params; // https://github.com/denizzzka/dpq2/blob/master/src/dpq2/args.d#L15
     params.preparedStatementName = "get_city_by_id";
-    params.argsVariadic(3);
+    params.argsVariadic(3); // https://github.com/denizzzka/dpq2/blob/master/example/example.d#L42  // https://github.com/denizzzka/dpq2/blob/master/src/dpq2/query.d#L336 // https://github.com/denizzzka/vibe.d.db.postgresql/blob/master/source/vibe/db/postgresql/package.d#L423
     auto result1 = conn.execPreparedStatement(params);
     
     writeln("id: ", result1[0]["id"].as!PGinteger);