Bump Docusaurus to 2.0 beta 4

Author: markerikson

website/package.json

@@ -9,8 +9,8 @@
     "deploy": "docusaurus deploy"
   },
   "dependencies": {
-    "@docusaurus/core": "2.0.0-beta.7babfe036",
-    "@docusaurus/preset-classic": "2.0.0-beta.7babfe036",
+    "@docusaurus/core": "2.0.0-beta.4",
+    "@docusaurus/preset-classic": "2.0.0-beta.4",
     "classnames": "^2.2.6",
     "react": "17.0.2",
     "react-dom": "17.0.2",