SDL_mixer: Updated note with which MP3 library we use by default

From 15343339105b94fe77a1eecc5ee5b6536a4007fd Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Fri, 20 May 2022 22:29:25 -0700
Subject: [PATCH] Updated note with which MP3 library we use by default

---
 README.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.txt b/README.txt
index 94d75d51..2577e29b 100644
--- a/README.txt
+++ b/README.txt
@@ -29,6 +29,6 @@ Support for software MIDI, MOD, and Opus are not included by default because of
 - When building with Xcode, you can edit the config at the top of the project to enable them, and you will need to include the appropriate framework in your application.
 - For Android, you can edit the config at the top of Android.mk to enable them.
 
-The default MP3 support is provided using minimp3. SDL_mixer also supports using libmad, but does not use it by default because the libmad license is GPL, which requires your application to also be GPL. If your application has a compatible license, you can enable libmad by passing
+The default MP3 support is provided using dr_mp3. SDL_mixer also supports using libmad, but does not use it by default because the libmad license is GPL, which requires your application to also be GPL. If your application has a compatible license, you can enable libmad by passing
 	--enable-music-mp3-mad
 to configure, or by defining MUSIC_MP3_MAD