Use the same create-plugin tutorial for FB and non-FB users

Summary: Per title

Reviewed By: passy

Differential Revision: D25558871

fbshipit-source-id: 85fbc73143a5ca172115169d08f8cdce502eb833

docs/tutorial/ios.mdx

@@ -3,6 +3,7 @@ id: ios
 title: Building an iOS Plugin
 ---
 import useBaseUrl from '@docusaurus/useBaseUrl';
+import {FbInternalOnly} from 'internaldocs-fb-helpers';
 
 <img alt="iOS Tutorial App" src={useBaseUrl("img/ios-tutorial-app.png")} />
 
@@ -15,6 +16,12 @@ You can find the source code of the project [on GitHub](https://github.com/faceb
 
 ## Creating a Plugin
 
+<FbInternalOnly>
+<div class="warning">
+[FB-Only] Depending the options selected during scaffolding (see intro), some of the following code might already have been generated by `scarf`. 
+</div>
+</FbInternalOnly>
+
 On iOS, a Flipper plugin is a class that implements the
 [`FlipperPlugin`](https://github.com/facebook/flipper/blob/master/iOS/FlipperKit/FlipperPlugin.h)
 interface.