Update header (#1632)

Author: bbejeck

index.html

@@ -38,7 +38,7 @@
             <h1>
               Say Hello World to Stream Processing
             </h1>
-            <h2 class="subtitle">From Idea to Proof-of-concept: Learn the Apache Kafka® fundamentals quickly with our functional tutorials, then explore the most popular stream processing use cases with recipes powered by ksqlDB so you can take immediate action, 100% in the cloud. <a href="https://www.confluent.io/confluent-cloud/tryfree/">Get started here</a></h2>
+            <h2 class="subtitle">From Idea to Proof-of-concept: Learn Apache Kafka® and Apache Flink® fundamentals quickly with our functional tutorials, then explore the most popular stream processing use cases with recipes powered by ksqlDB so you can take immediate action, 100% in the cloud. <a href="https://www.confluent.io/confluent-cloud/tryfree/">Get started here</a></h2>
             <div class="ctas">
                 <a href="{{ "/index.html" | relative_url }}" class="btn-midnight-white-outline">Concepts</a>
                 <a href="{{ "/use-cases.html" | relative_url }}" class="btn-midnight">Use Case Recipes</a>