Added migration notes for enum type changes

docs/README-migration.md

@@ -859,6 +859,8 @@ The following functions have been renamed:
 
 ## SDL_keycode.h
 
+SDL_Keycode is now an enum instead of Sint32.
+
 The following symbols have been renamed:
 * KMOD_ALT => SDL_KMOD_ALT
 * KMOD_CAPS => SDL_KMOD_CAPS
@@ -946,6 +948,8 @@ SDL_CalculateGammaRamp has been removed, because SDL_SetWindowGammaRamp has been
 
 The BitsPerPixel and BytesPerPixel fields of SDL_PixelFormat have been renamed bits_per_pixel and bytes_per_pixel.
 
+SDL_PixelFormatEnum is used instead of Uint32 for API functions that refer to pixel format by enumerated value.
+
 The following functions have been renamed:
 * SDL_AllocFormat() => SDL_CreatePixelFormat()
 * SDL_AllocPalette() => SDL_CreatePalette()
@@ -1402,6 +1406,8 @@ SDL_BlitSurfaceScaled() and SDL_BlitSurfaceUncheckedScaled() now take a scale pa
 
 SDL_SoftStretch() now takes a scale paramater.
 
+SDL_PixelFormatEnum is used instead of Uint32 for API functions that refer to pixel format by enumerated value.
+
 The following functions have been renamed:
 * SDL_FillRect() => SDL_FillSurfaceRect()
 * SDL_FillRects() => SDL_FillSurfaceRects()
@@ -1658,6 +1664,9 @@ SDL_GL_GetDrawableSize() has been removed. SDL_GetWindowSizeInPixels() can be us
 
 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.
 
+
+SDL_WindowFlags is used instead of Uint32 for API functions that refer to window flags.
+
 The following functions have been renamed:
 * SDL_GetClosestDisplayMode() => SDL_GetClosestFullscreenDisplayMode()
 * SDL_GetDisplayOrientation() => SDL_GetCurrentDisplayOrientation()