Add postbuild script to copy rss feed

package.json

@@ -9,6 +9,7 @@
     "docusaurus": "docusaurus",
     "start": "docusaurus start",
     "build": "docusaurus build",
+    "postbuild": "node ./scripts/copy-rss-feed.js",
     "swizzle": "docusaurus swizzle",
     "clear": "docusaurus clear",
     "serve": "docusaurus serve",

scripts/copy-rss-feed.js

@@ -0,0 +1,14 @@
+const fs = require('fs');
+const path = require('path');
+
+fs.copyFile(
+  path.resolve(__dirname, '../build/posts/rss.xml'),
+  path.resolve(__dirname, '../build/index.xml'),
+  (error) => {
+    if (error) {
+      throw error;
+    } else {
+      console.log('RSS feed has been copied to index.xml');
+    }
+  }
+);