Document sizes

docs/api/app.md

@@ -405,16 +405,23 @@ You can request the following paths by the name:
 
 * `path` String
 * `options` Object (optional)
-  * `size` String - Can be `small`, `normal`, `large`. The `large` size is not supported on _macOS_
+  * `size` String
+    * `small` - 16x16
+    * `normal` - 32x32
+    * `large` - 48x48. This size is not supported on _macOS_.
 * `callback` Function
   * `error` Error
   * `icon` [NativeImage](native-image.md)
 
-Fetches associated icon for using OS rules for handling icons.
+Fetches a path's associated icon.
+
 On _Windows_, there a 2 kinds of icons:
-- icons associated with certain file extension - `.mp3`, `.png`, etc.
-- icons inside file itself, like `.exe`, `.dll`, `.ico`.
-On _Linux_ and _macOS_, icons depend on application associated with file mime type.
+
+- Icons associated with certain file extensions, like `.mp3`, `.png`, etc.
+- Icons inside the file itself, like `.exe`, `.dll`, `.ico`.
+
+On _Linux_ and _macOS_, icons depend on the application associated with file
+mime type.
 
 ### `app.setPath(name, path)`