Add Docusaurus Umami plugin

Author: markerikson

website/package.json

@@ -9,6 +9,7 @@
     "serve": "docusaurus serve"
   },
   "dependencies": {
+    "@dipakparmar/docusaurus-plugin-umami": "^2.0.6",
     "@docusaurus/core": "2.0.0-beta.7",
     "@docusaurus/preset-classic": "2.0.0-beta.7",
     "classnames": "^2.2.6",