docs: add changelog (#15606)

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---------

Co-authored-by: Harrison Chase <hw.chase.17@gmail.com>

docs/sidebars.js

@@ -142,6 +142,14 @@ module.exports = {
       link: { type: 'doc', id: "templates/index" }
     },
   ],
+  changelog: [
+    {
+      type: "category",
+      label: "Changelog",
+      items: [{ type: "autogenerated", dirName: "changelog" }],
+      link: { type: 'generated-index', slug: "changelog"}
+    },
+  ],
   contributing: [
     {type: "autogenerated", dirName: "contributing" }
   ],