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/js-setup.mdx

@@ -4,6 +4,7 @@ title: Building a Desktop Plugin
 sidebar_label: Building a Desktop Plugin
 ---
 import useBaseUrl from '@docusaurus/useBaseUrl';
+import {FbInternalOnly, OssOnly} from 'internaldocs-fb-helpers';
 
 Now that we have the native side covered, let's display the data we're sending
 on the desktop side. You can check out the full workflow of building Flipper desktop
@@ -13,6 +14,12 @@ plugins here: https://fbflipper.com/docs/extending/js-setup.
 
 ## Dynamic Plugin loading
 
+<FbInternalOnly>
+[FB-Only] After scaffolding and starting Flipper from source, no further steps are needed to setup the desktop plugin. 
+</FbInternalOnly>
+
+<OssOnly>
+
 By default, Flipper will start with the plugins it was bundled with. You can
 configure it to also look for plugins in custom directories. To do that,
 modify the `~/.flipper/config.json` file that is created the first time
@@ -84,3 +91,5 @@ For instance:
 To ensure there are no errors in the defined plugin, install packages (using `yarn install` or `npm install`) and execute script `lint` (`yarn lint` or `npm run lint`) which shows all the mismatches that should be fixed to make the plugin definition valid.
 
 Now that our package has been set up, we are ready to build a UI for our plugin. Either by using a standardized table-based plugin, or by creating a custom UI.
+
+</OssOnly>