Add forum page click to GA (#5458) (#5467)

(cherry picked from commit b5ed6c7)

Signed-off-by: Fanit Kolchina <kolchfa@amazon.com>
Signed-off-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

_includes/feedback.html

@@ -11,6 +11,6 @@
     <div class="text-small num-chars" id="num-chars">350 characters left</div>
     <button id="send" class="send-button" disabled>Send</button>
     <p class="text-small text-grey-dk-100 hidden" id="thank-you">Thank you for your feedback!</p>
-    <p class="text-small text-grey-dk-100">Have a question? <a target="_blank" href="https://forum.opensearch.org/">Ask us on the OpenSearch forum</a>.</p>
+    <p class="text-small text-grey-dk-100">Have a question? <a class="feedback-forum" target="_blank" href="https://forum.opensearch.org/">Ask us on the OpenSearch forum</a>.</p>
     <p class="text-small text-grey-dk-100">Want to contribute? <a class="feedback-edit" target="_blank" href="https://github.com/opensearch-project/documentation-website/edit/main/{{ page.path }}">Edit this page</a> or <a class="feedback-issue" target="_blank" href="https://github.com/opensearch-project/documentation-website/issues/new?assignees=&labels=untriaged&template=issue_template.md&title=%5BDOC%5D">create an issue</a>.</p>
 </div>

assets/js/listener.js

@@ -15,6 +15,9 @@ document.addEventListener('click', function(event) {
     else if (target.matches('.feedback-edit')) {
         gtag('event', 'edit_page_click');
     }
+    else if (target.matches('.feedback-forum')) {
+        gtag('event', 'forum_link_click');
+    }
     else if (target.matches('.feedback-button')) {
         sendButton.disabled = false;
     }