Update highlighting for onCreate method for clarity

it seems by the description that you should just edit the function but in fact you need to add the onCreate function in MainActivity as its not there in the template.

Author: dannyhw

versioned_docs/version-7.x/getting-started.md

@@ -99,12 +99,14 @@ import com.swmansion.rnscreens.fragment.restoration.RNScreensFragmentFactory
 
 class MainActivity: ReactActivity() {
   // ...
+
+  // highlight-start
   override fun onCreate(savedInstanceState: Bundle?) {
-    // highlight-start
     supportFragmentManager.fragmentFactory = RNScreensFragmentFactory()
     super.onCreate(savedInstanceState)
-    // highlight-end
   }
+  // highlight-end
+
   // ...
 }
 ```