增加：微信公众平台-系统公告栏目 (#895)

- 实现 #883 
- 没找到比较合适的分类，暂时先放到`程序更新`下面
- 由于正文内容是放在 `window.wxCgi` 中，输出的话需要出动 `puppeteer` 来搞，感觉意义不太大而且资源消耗也大，所以暂时未输出正文内容。后续如有需要再添加（其实用正则去匹配也不是不行（光速逃
- 最后有个疑问点：爬取到的链接中有这样的`https://mp.weixin.qq.com/cgi-bin/announce?action=getannouncement&announce_id=11531387046zmIME&version=&lang=zh_CN`，中间带有`&`这类特殊符号，试了下发现输出为 `json` 格式时会转义掉变成这样`https://mp.weixin.qq.com/cgi-bin/announce?action=getannouncement&announce_id=11531387046zmIME&version=&lang=zh_CN`，是无法直接使用了，好奇下这是个 bug 还是说设计如此(feature)？（还没来得及看这部分的处理逻辑

docs/README.md

@@ -937,6 +937,10 @@ GitHub 官方也提供了一些 RSS:
 
 <route name="应用更新" author="DIYgod" example="/xclient/app/sketch" path="/xclient/app/:name" :paramsDesc="['应用名, 可在应用页 URL 中找到']"/>
 
+### 微信公众平台
+
+<route name="系统公告栏目" author="xyqfer" example="/wechat/announce" path="/wechat/announce" />
+
 ## 大学通知
 
 ### 上海海事大学

router.js

@@ -451,6 +451,7 @@ router.get('/hopper/:lowestOnly/:from/:to?', require('./routes/hopper/index'));
 
 // wechat
 router.get('/wechat/wasi/:id', require('./routes/wechat/wasi'));
+router.get('/wechat/announce', require('./routes/wechat/announce'));
 
 // 马蜂窝
 router.get('/mafengwo/note/:type', require('./routes/mafengwo/note'));

routes/wechat/announce.js

@@ -0,0 +1,32 @@
+const axios = require('../../utils/axios');
+const cheerio = require('cheerio');
+
+module.exports = async (ctx) => {
+    const { data: htmlString } = await axios({
+        method: 'get',
+        url: 'https://mp.weixin.qq.com/cgi-bin/announce?action=getannouncementlist&lang=zh_CN',
+    });
+
+    const $ = cheerio.load(htmlString);
+    const announceList = [];
+
+    $('.mp_news_list > .mp_news_item').each(function() {
+        const $item = $(this);
+        const $link = $item.find('a');
+        const time = $item.find('.read_more').text();
+        const title = $item.find('strong').text();
+
+        announceList.push({
+            title: `${time} ${title}`,
+            link: `https://mp.weixin.qq.com${$link.attr('href')}`,
+            description: title,
+            pubDate: new Date(time).toUTCString(),
+        });
+    });
+
+    ctx.state.data = {
+        title: '微信公众平台-系统公告栏目',
+        link: 'https://mp.weixin.qq.com/cgi-bin/announce?action=getannouncementlist&lang=zh_CN&token=',
+        item: announceList,
+    };
+};