✨ RSS Feed for the blog and "What's New" page

### Description

RSS is a standard for providing articles and other web content in a machine-readable feed which can be fetched by clients and served to users in their app of choice. Creating RSS feeds for the blog and the "What's New" would allow people to easily keep up-to-date with the CodeEdit blog and CodeEdit updates without having to check the website manually.

### Alternatives Considered

Setting up an email list would accomplish the same goal of allowing people to keep up-to-date with blog articles and updates without having to check the website manually, and email is a more widely-used standard than RSS. However, running an email list would be significantly more complex and costly than simply providing an RSS feed, and it would not give users the same amount of choice in how they read blog articles/updates.

### Additional Context

The [RSS Specification](https://www.rssboard.org/rss-specification) allows either a summary or the full content of each item in the `` tag. I think CodeEdit should include the full content, because it makes for a more pleasant reading experience, although it does make the feed slightly larger.

### Screenshots

_No response_

先在 repository 中找出部落格和「What’s New」頁面的進入點，並檢視其文章的表示方式。使用 issue 中連結的 RSS Specification，接著確認兩個 feed 都可擷取，並公開各自 item 的完整內容。

由索引模型根據 Issue 內容生成。