Make index page's ranklist's count configurable

config-example.json

@@ -52,6 +52,7 @@
     "problem": 50,
     "problem_statistics": 10,
     "judge_state": 10,
+    "ranklist_index": 20,
     "ranklist": 20,
     "discussion": 10,
     "article_comment": 10,

modules/index.js

@@ -31,7 +31,7 @@ const timeAgo = new TimeAgo('zh-CN');
 
 app.get('/', async (req, res) => {
   try {
-    let ranklist = await User.query([1, 10], { is_show: true }, [[syzoj.config.sorting.ranklist.field, syzoj.config.sorting.ranklist.order]]);
+    let ranklist = await User.query([1, syzoj.config.page.ranklist_index || 3], { is_show: true }, [[syzoj.config.sorting.ranklist.field, syzoj.config.sorting.ranklist.order]]);
     await ranklist.forEachAsync(async x => x.renderInformation());
 
     let notices = (await Article.query(null, { is_notice: true }, [['public_time', 'desc']])).map(article => ({