SDL3_mixer/FrontPage: Added some useful links.

Live page is here: https://wiki.libsdl.org/SDL3_mixer/FrontPage

Author: icculus

SDL3_mixer/FrontPage.md

@@ -7,6 +7,12 @@ SDL_mixer 3.0 (aka "SDL3_mixer") is a library to manage audio in SDL3-based game
 It offers audio file decoding for several popular formats, such as WAV, MP3, and Ogg Vorbis, and provides sample-perfect mixing of multiple sources of audio, with various effects, and other advanced features.
 
 It is available under the zlib license, found in the file [LICENSE.txt](https://github.com/libsdl-org/SDL_mixer/blob/main/LICENSE.txt).
-The API is listed in [CategorySDLMixer](CategorySDLMixer).
+
+Useful links:
+
+- An overview of the API, and links to documentation on all public symbols, is listed in [CategorySDLMixer](CategorySDLMixer).
+- We offer a [Quick Reference card](QuickReference) to see the whole API in an extremely-condensed form.
+- There is a [Migration Guide](README-migration) to help you move here from SDL2_mixer's API.
 
 Enjoy!
+