chore: Modified a label for readability.

index.html

@@ -29,7 +29,7 @@ <h2>武器の現状</h2>
   <h2>ターゲット</h2>
   <ul>
     <li>
-      <label for="to-level-input">上げたい九十九レベル</label>
+      <label for="to-level-input">目標の九十九レベル</label>
       <input type="number" name="to-level" id="to-level-input" value="1" step="1" min="1" max="31">
     </li>
     <li>