SimpleChat: placeholder based usage hint for user-in textarea

Author: hanishkvc

examples/server/public_simplechat/index.html

@@ -40,7 +40,7 @@
 
             <hr>
             <div class="sameline">
-                <textarea id="user-in" class="flex-grow" rows="3"></textarea>
+                <textarea id="user-in" class="flex-grow" rows="3" placeholder="enter your query to the ai model here" ></textarea>
                 <button id="user-btn">submit</button>
             </div>