SDL: include: Add documentation to SDL_MessageBoxColorType.

From 7ab8e4797e5ef0d9f29e06110c0843fa338192f6 Mon Sep 17 00:00:00 2001
From: anon <[EMAIL REDACTED]>
Date: Thu, 11 Apr 2024 20:31:11 +0200
Subject: [PATCH] include: Add documentation to SDL_MessageBoxColorType.

---
 include/SDL3/SDL_messagebox.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/SDL3/SDL_messagebox.h b/include/SDL3/SDL_messagebox.h
index f30b22623c3d5..7e2ee80d2caaf 100644
--- a/include/SDL3/SDL_messagebox.h
+++ b/include/SDL3/SDL_messagebox.h
@@ -81,6 +81,9 @@ typedef struct SDL_MessageBoxColor
     Uint8 r, g, b;
 } SDL_MessageBoxColor;
 
+/**
+ * An enumeration of indices inside the colors array of SDL_MessageBoxColorScheme.
+ */
 typedef enum SDL_MessageBoxColorType
 {
     SDL_MESSAGEBOX_COLOR_BACKGROUND,
@@ -88,7 +91,7 @@ typedef enum SDL_MessageBoxColorType
     SDL_MESSAGEBOX_COLOR_BUTTON_BORDER,
     SDL_MESSAGEBOX_COLOR_BUTTON_BACKGROUND,
     SDL_MESSAGEBOX_COLOR_BUTTON_SELECTED,
-    SDL_MESSAGEBOX_COLOR_MAX
+    SDL_MESSAGEBOX_COLOR_MAX                    /**< Size of the colors array of SDL_MessageBoxColorScheme. */
 } SDL_MessageBoxColorType;
 
 /**