Update src/index.php

Групповые бои. #3

src/index.php

@@ -8,6 +8,12 @@
 <h1>Battle</h1>
 <form id="joinForm">
     <input type="text" id="username" placeholder="Enter your name" required>
+    <select id="gameMode" required>
+        <option value="" disabled selected>Select game mode</option>
+        <option value="solo">Solo</option>
+        <option value="team">Team</option>
+    </select>
+    <input id="team" type="number" style="display: none;">
     <button type="submit">Join Game</button>
 </form>
 <div id="gameContainer" style="display: none;">