Add clarifications to the documentation

docs/api/app.md

@@ -892,10 +892,10 @@ details.
 
 ### `app.setAccessibilitySupportEnabled(enabled)` _macOS_ _Windows_
 
-* `enabled` Boolean - Enable or disable accessibility tree rendering
+* `enabled` Boolean - Enable or disable [accessibility tree](https://developers.google.com/web/fundamentals/accessibility/semantics-builtin/the-accessibility-tree) rendering
 
 Manually enables Chrome's accessibility support, allowing to expose accessibility switch to users in application settings. https://www.chromium.org/developers/design-documents/accessibility for more
-details.
+details. Disabled by default.
 
 **Note:** Rendering accessibility tree can significantly affect the performance of your app. It should not be enabled by default.
 

docs/tutorial/accessibility.md

@@ -38,13 +38,13 @@ Electron applications keep accessibility disabled by default for performance rea
 
 ### Inside Application
 
-By using [`app.setAccessibilitySupportEnabled(enabled)`](https://electron.atom.io/docs/api/app.md#appsetaccessibilitysupportenabledenabled-macos-windows), you can expose accessibility switch to users in the application preferences.
+By using [`app.setAccessibilitySupportEnabled(enabled)`](https://electron.atom.io/docs/api/app.md#appsetaccessibilitysupportenabledenabled-macos-windows), you can expose accessibility switch to users in the application preferences. User's system assistive utilities have priority over this setting and will override it.
 
 ### Assistive Technology
 
 Electron application will enable accessibility automatically when it detects assistive technology (Windows) or VoiceOver (macOS). See Chrome's [accessibility documentation](https://www.chromium.org/developers/design-documents/accessibility#TOC-How-Chrome-detects-the-presence-of-Assistive-Technology) for more details.
 
-On macOS 3rd party assistive technology can switch accessibility inside Electron applications by setting the attribute `AXManualAccessibility` programmatically:
+On macOS, thrid-party assistive technology can switch accessibility inside Electron applications by setting the attribute `AXManualAccessibility` programmatically:
 
 ```objc
 CFStringRef kAXManualAccessibility = CFSTR("AXManualAccessibility");