Fix: Update discussion forum URL to correct domain

- Changed from http://discuss.meshery.io/ to https://discuss.layer5.io/
- Fixes broken link in 'Join the Conversation' section
- Resolves meshery/meshery#16152

Signed-off-by: shri33 <your-email@example.com>

Author: shri33

site/src/components/Discuss-Callout/index.js

@@ -9,7 +9,7 @@ const DiscussCallout = () => {
       <div className="explain">
         <div className="cards">
           <div className="card">
-            <a href="http://discuss.meshery.io/">
+            <a href="https://discuss.layer5.io/">
               <div className="parentcard">
                 <div className="section-title">
                   <h2>Join the Conversation</h2>