docs(jsonp): modernize jQuery calls in example

Replace deprecated jQuery APIs in the JSONP client demo:
- $(document).ready(fn) -> $(fn)
- .click(fn) -> .on("click", fn)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: vishr

site/src/content/docs/cookbook/jsonp.md

@@ -66,9 +66,9 @@ func main() {
     <script type="text/javascript" src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
     <script type="text/javascript">
         var host_prefix = 'http://localhost:1323';
-        $(document).ready(function() {
+        $(function() {
             // JSONP version - add 'callback=?' to the URL - fetch the JSONP response to the request
-            $("#jsonp-button").click(function(e) {
+            $("#jsonp-button").on("click", function(e) {
                 e.preventDefault();
                 // The only difference on the client end is the addition of 'callback=?' to the URL
                 var url = host_prefix + '/jsonp?callback=?';