fix typo in #INSTRUMENTAL example code

docs/index.html

@@ -1600,7 +1600,7 @@ <h4 class="text-red"><a id="vocals" href="#vocals"></a>VOCALS (new)</h4>
                     <h4 class="text-red"><a id="instrumental" href="#instrumental"></a>INSTRUMENTAL (new)</h4>
                     <p>#INSTRUMENTAL defines the audio file that contains only the instruments of a song without the singers voice. This is for real karaoke. Please add to the file name [INSTR].</p>
                     <div>
-                        <pre class="notranslate"><code>#INSTRUMENTALS: Artist - Title of the song [INSTR].mp3
+                        <pre class="notranslate"><code>#INSTRUMENTAL: Artist - Title of the song [INSTR].mp3
                     </code></pre>
                     <details>
                         <summary>App Support</summary>