SDL_ttf: Added a migration note for background/foreground alpha values

From dd63932c5c885a89f091ca4470aee5350f2b4ea3 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Fri, 27 Sep 2024 01:53:18 -0700
Subject: [PATCH] Added a migration note for background/foreground alpha values

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

diff --git a/docs/README-migration.md b/docs/README-migration.md
index eec1d4d4..0fb6ceb2 100644
--- a/docs/README-migration.md
+++ b/docs/README-migration.md
@@ -38,6 +38,8 @@ In general we have switched to using UTF8 in the API. Functions which had 3 vari
 
 The solid color rendering functions have been removed in favor of the higher quality shaded and blended functions.
 
+The alpha in background and foreground colors is now transparent if it's equal to 0.
+
 The following functions have been renamed:
 * TTF_FontAscent() => TTF_GetFontAscent()
 * TTF_FontDescent() => TTF_GetFontDescent()