use api v2 for add comment

src/Common.js

@@ -16,6 +16,7 @@ import renderMd from './Markdown';
 export { format_time, Time, TitleLine };
 
 export const API_BASE = `${process.env.REACT_APP_BACKEND || '/'}_api/v1`;
+export const API_BASE_2 = `${process.env.REACT_APP_BACKEND || '/'}_api/v2`;
 
 // https://stackoverflow.com/questions/3446170/escape-string-for-use-in-javascript-regex
 function escape_regex(string) {

src/UserAction.js

@@ -1,6 +1,7 @@
 import React, { Component } from 'react';
 import {
   API_BASE,
+  API_BASE_2,
   SafeTextarea,
   PromotionBar,
   HighlightedMarkdown,
@@ -395,11 +396,10 @@ export class ReplyForm extends Component {
     const { pid } = this.props;
     const { text, use_title } = this.state;
     let data = new URLSearchParams({
-      pid: pid,
       text: text,
       use_title: use_title ? '1' : '',
     });
-    fetch(API_BASE + '/docomment', {
+    fetch(`${API_BASE_2}/post/${pid}/comment`, {
       method: 'POST',
       headers: {
         'Content-Type': 'application/x-www-form-urlencoded',