SDL_mixer: fix returned value documentation for Mix_FadeOutChannel.

From 6dd56a7cbf3efe4b5a4ac86ab47771a9f2ca5a8c Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Thu, 20 Oct 2022 01:00:00 +0300
Subject: [PATCH] fix returned value documentation for Mix_FadeOutChannel.

Fixes https://github.com/libsdl-org/SDL_mixer/issues/456
---
 include/SDL_mixer.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/SDL_mixer.h b/include/SDL_mixer.h
index b4ad5364..bd877535 100644
--- a/include/SDL_mixer.h
+++ b/include/SDL_mixer.h
@@ -2187,7 +2187,7 @@ extern DECLSPEC int SDLCALL Mix_ExpireChannel(int channel, int ticks);
  *
  * \param which the channel to fade out.
  * \param ms number of milliseconds to fade before halting the channel.
- * \returns 0 on success, or -1 on error.
+ * \returns the number of channels scheduled to fade.
  *
  * \since This function is available since SDL_mixer 2.0.0.
  */