feat: add explanatory note to open-source rank page

- Add note explaining GitHub repository display criteria
- Support for English, Simplified Chinese, and German

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: ericyangpan

messages/de.json

@@ -492,6 +492,7 @@
       "filter": {
         "all": "Alle"
       },
+      "note": "Hinweis: Diese Seite zeigt nur Projekte mit GitHub-Repositories. Einige Projekte, obwohl nicht Open Source, unterhalten GitHub-Repositories als Feedback-Kanäle für Benutzer.",
       "productType": {
         "ide": "IDE",
         "cli": "CLI",

messages/en.json

@@ -488,6 +488,7 @@
       "filter": {
         "all": "All"
       },
+      "note": "Note: This page only shows projects with GitHub repositories. Some projects, while not open source, maintain GitHub repositories as user feedback channels.",
       "productType": {
         "ide": "IDE",
         "cli": "CLI",

messages/zh-Hans.json

@@ -482,6 +482,7 @@
       "filter": {
         "all": "全部"
       },
+      "note": "注意：此页面仅显示有 GitHub 地址的项目。部分项目虽未开源，但会创建 GitHub 仓库作为用户反馈入口。",
       "productType": {
         "ide": "IDE",
         "cli": "CLI",