added basic dev server instructions back into site README

Author: austinbfraser

mlflow-site/README.md

@@ -0,0 +1,15 @@
+## Getting Started
+
+First, run the development server:
+
+```bash
+npm run dev
+# or
+yarn dev
+# or
+pnpm dev
+# or
+bun dev
+```
+
+Open [http://localhost:3000](http://localhost:3000) with your browser to see the result.