Update 'Attend KubeCon' buttons

Author: jihoon-seo

content/en/_index.html

@@ -43,12 +43,12 @@ <h2>The Challenges of Migrating 150+ Microservices to Kubernetes</h2>
         <button id="desktopShowVideoButton" onclick="kub.showVideo()">Watch Video</button>
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         <br>
-        <a href="https://events.linuxfoundation.org/kubecon-cloudnativecon-north-america/?utm_source=kubernetes.io&utm_medium=nav&utm_campaign=kccncna20" button id="desktopKCButton">Attend KubeCon NA virtually on November 17-20, 2020</a>
+        <a href="https://events.linuxfoundation.org/kubecon-cloudnativecon-north-america/?utm_source=kubernetes.io&utm_medium=nav&utm_campaign=kccncna21" button id="desktopKCButton">Attend KubeCon North America on October 11-15, 2021</a>
         <br>
         <br>
         <br>
         <br>
-        <a href="https://events.linuxfoundation.org/kubecon-cloudnativecon-europe/?utm_source=kubernetes.io&utm_medium=nav&utm_campaign=kccnceu21" button id="desktopKCButton">Attend KubeCon EU virtually on May 4 – 7, 2021</a>
+        <a href="https://events.linuxfoundation.org/kubecon-cloudnativecon-europe/?utm_source=kubernetes.io&utm_medium=nav&utm_campaign=kccnceu21" button id="desktopKCButton">Revisit KubeCon EU 2021</a>
 </div>
 <div id="videoPlayer">
     <iframe data-url="https://www.youtube.com/embed/H06qrNmGqyE?autoplay=1" frameborder="0" allowfullscreen></iframe>
@@ -58,4 +58,4 @@ <h2>The Challenges of Migrating 150+ Microservices to Kubernetes</h2>
 
 {{< blocks/kubernetes-features >}}
 
-{{< blocks/case-studies >}}
+{{< blocks/case-studies >}}