Add Extension Development Mode option

Author: quinntracy

content/en/docs/refguide/modeling/menus/edit-menu/preferences-dialog.md

@@ -281,6 +281,10 @@ When the **Show feedback survey periodically** setting is enabled, Studio Pro wi
 
 When the **Do not show antivirus exclusion notifications** setting is enabled, Studio Pro will not display notifications related to antivirus exclusions. For more information, see [Antivirus Exclusion](/refguide/antivirus-exclusion/).
 
+### Extension Development 
+
+When **Extension Development** mode is enabled, you can start Studio Pro without using the extensibility feature flag. You must restart Studio Pro to use this feature.
+
 ## New Features Tab {#new-features}
 
 ### App Explorer