Document normalizeAccessKeys option

docs/api/dialog.md

@@ -35,6 +35,14 @@ The `dialog` module has the following methods:
   * `properties` String[] (optional) - Contains which features the dialog should use, can
     contain `openFile`, `openDirectory`, `multiSelections`, `createDirectory`
     and `showHiddenFiles`.
+  * `normalizeAccessKeys` Boolean (optional) - Normalize the keyboard access keys
+    across platforms. Default is `false`. Enabling this assumes `&` is used in
+    the button labels for the placement of the keyboard shortcut access key
+    and labels will be converted so they work correctly on each platform, `&`
+    characters are removed on macOS, converted to `_` on Linux, and left
+    untouched on Windows. For example, a button label of `Vie&w` will be
+    converted to `Vie_w` on Linux and `View` on macOS and can be selected
+    via `Alt-W` on Windows and Linux.
 * `callback` Function (optional)
   * `filePaths` String[] - An array of file paths chosen by the user