SDL: docs: Update the migration document with changes to the tooltips and popup menu flags.

From 5a0f50e1c3a8c224b1881743c37b21c872c83850 Mon Sep 17 00:00:00 2001
From: Frank Praznik <[EMAIL REDACTED]>
Date: Fri, 3 Mar 2023 19:05:57 -0500
Subject: [PATCH] docs: Update the migration document with changes to the
 tooltips and popup menu flags.

---
 docs/README-migration.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/docs/README-migration.md b/docs/README-migration.md
index 24bf248cbeb6..a2b68fe03860 100644
--- a/docs/README-migration.md
+++ b/docs/README-migration.md
@@ -1092,6 +1092,8 @@ SDL_GL_GetSwapInterval() takes the interval as an output parameter and returns 0
 
 SDL_GL_GetDrawableSize() has been removed. SDL_GetWindowSizeInPixels() can be used in its place.
 
+The SDL_WINDOW_TOOLTIP and SDL_WINDOW_POPUP_MENU window flags are now supported on Windows, Mac (Cocoa), X11, and Wayland. Creating windows with these flags must happen via the `SDL_CreatePopupWindow()` function. This function requires passing in the handle to a valid parent window for the popup, and the popup window is positioned relative to the parent.
+
 The following functions have been renamed:
 * SDL_GetClosestDisplayMode() => SDL_GetClosestFullscreenDisplayMode()
 * SDL_GetPointDisplayIndex() => SDL_GetDisplayForPoint()