Add small tutorial

src/js/platform/browser/sound.js

@@ -104,7 +104,7 @@ class MusicInstance extends MusicInstanceInterface {
             }),
             new Promise((resolve, reject) => {
                 this.howl = new Howl({
-                    src: cachebust("res/sounds/music/" + this.url),
+                    src: cachebust("res/sounds/music/" + this.url + ".mp3"),
                     autoplay: false,
                     loop: true,
                     html5: true,

src/js/platform/sound.js

@@ -27,8 +27,8 @@ export const SOUNDS = {
 };
 
 export const MUSIC = {
-    theme: "theme.mp3",
-    menu: "menu.mp3",
+    theme: "theme",
+    menu: "menu",
 };
 
 export class SoundInstanceInterface {