Update index.html - fix fat finger on racp23-4

Author: chuynh18

index.html

@@ -82,7 +82,7 @@ <h1 id="titleText">Digital Piano with MIDI Playback</h1>
                   <option value="6550d_heroic_polonaise_(c)smythe">Polonaise in A♭ major, Op. 53, “Heroic” – Chopin</option>
                   <option value="polonaise_op_44_669_r_(nc)smythe">Polonaise in F♯ minor, Op. 44 – Chopin</option>
                   <option value="rach0302">Prelude in C♯ minor, Op. 3 – Rachmaninoff</option>
-                  <option value="rach2305">Prelude No. 4 in D major, Op. 23 – Rachmaninoff</option>
+                  <option value="racp23-4">Prelude No. 4 in D major, Op. 23 – Rachmaninoff</option>
                   <option value="rach2305">Prelude No. 5 in G minor, Op. 23 – Rachmaninoff</option>
                   <option value="donizetti_59303a_lucia_di_lammermoor_(nc)smythe">Réminiscences de Lucia di Lammermoor, S.397 – Donizetti/Liszt</option>
                   <option value="rhapsody_in_blue">Rhapsody in Blue – Gershwin</option>
@@ -112,4 +112,4 @@ <h1 id="titleText">Digital Piano with MIDI Playback</h1>
    <script type="module" src="assets/js/fullkeyboardtest.js"></script>
 </body>
 
-</html>
+</html>