docs: add mobx_utils page

Author: amondnet

docs/docs/guides/mobx-utils.mdx

@@ -0,0 +1,11 @@
+---
+title: MobX-utils
+sidebar_label: MobX-utils {🚀}
+hide_title: true
+---
+
+<script async type="text/javascript" src="//cdn.carbonads.com/carbon.js?serve=CEBD4KQ7&placement=mobxjsorg" id="_carbonads_js"></script>
+
+# MobX-utils {🚀}
+
+[mobx_utils](https://pub.dev/packages/mobx_utils) provides an extensive series of additional utility functions, observables and common patterns for MobX.

docs/sidebars.js

@@ -28,6 +28,7 @@ module.exports = {
         'guides/json-serialization',
         'guides/organizing-stores',
         'guides/when-does-mobx-react',
+        'guides/mobx-utils',
       ],
     },
     'community',