ViewController: add some additional documentation (NFC)

Add some documentation comments for `ModalTransitionStyle`.

Author: compnerd

Sources/SwiftWin32/View Controllers/ViewController.swift

@@ -6,9 +6,41 @@ import class Foundation.NSNotification
 
 /// Transition styles available when presenting view controllers.
 public enum ModalTransitionStyle: Int {
+  ///
+  ///
+  /// When the view controller is presented, its view slides up from the bottom
+  /// of the screen. On dismissal, the view slides back down. This is the
+  /// default transition style.
   case coverVertical
+
+  ///
+  ///
+  /// When the view controller is presented, the current view initiates a
+  /// horizontal 3D flip from right-to-left, resulting in the revealing of the
+  /// new view as if it were on the back of the previous view. On dismissal, the
+  /// flip occurs from left-to-right, returning to the original view.
   case flipHorizontal
+
+  ///
+  ///
+  /// When the view controller is presented, the current view fades out while
+  /// the new view fades in at the same time. On dismissal, a similar type of
+  /// cross-fade is used to return to the original view.
   case crossDissolve
+
+  ///
+  ///
+  /// When the view controller is presented, one corner of the current view
+  /// curls up to reveal the presented view underneath. On dismissal, the curled
+  /// up page unfurls itself back on top of the presented view. A view
+  /// controller presented using this transition is itself prevented from
+  /// presenting any additional view controllers.
+  ///
+  /// This transition style is supported only if the parent view controller is
+  /// presenting a full-screen view and you use the
+  /// `ModalPresentationStyle.fullScreen` modal presentation style. Attempting
+  /// to use a different form factor for the parent view or a different
+  /// presentation style triggers an exception.
   case partialCurl
 }