chore: update docs

Author: hashemix

docs/_media/favicon.png

@@ -28,6 +28,8 @@
   <meta name="twitter:image:alt" content="Rust MCP Filesystem">
   <meta name="twitter:site" content="@rustmcp">
 
+  <link rel="icon" type="image/png" href="_media/favicon.png">
+
   <link rel="stylesheet" href="//cdn.jsdelivr.net/npm/docsify@4/lib/themes/vue.css">