docs: update readme and posts

pages/_document.js

@@ -21,7 +21,7 @@ class MyDocument extends Document {
           <link rel="mask-icon" href="/static/favicons/safari-pinned-tab.svg" color="#5bbad5" />
           <meta name="msapplication-TileColor" content="#000000" />
           <meta name="theme-color" content="#000000" />
-          <link rel="alternate" type="application/rss+xml" href="/index.xml" />
+          <link rel="alternate" type="application/rss+xml" href="/feed.xml" />
           <link rel="preconnect" href="https://fonts.gstatic.com" crossOrigin="anonymous" />
           <link
             href="https://fonts.googleapis.com/css2?family=Inter:wght@400;600;700&display=swap"