fix: update Slack community links to use marketing opt-in page (#266)

Author: ktx-krupa

overrides/partials/index.html

@@ -457,7 +457,7 @@ <h3>WINDOWS</h3>
         <h2 class="landing-section-title">Community & Support</h2>
         <div class="landing-community-support-grid">
           <a
-            href="https://short.openobserve.ai/community"
+            href="/marketing-opt-in/"
             class="landing-community-support-item"
             data-clarity-event="docs_landing_page_card_click"
             data-clarity-title="Community"