HOTFIX: fix Kafka Streams upgrade note for broker backward compatibil…

…ity (#7363)

Reviewer: Guozhang Wang <guozhang@confluent.io>

docs/streams/upgrade-guide.html

@@ -53,8 +53,10 @@ <h1>Upgrade Guide and API Changes</h1>
     </ul>
 
     <p>
-        Note, that a brokers must be on version 0.10.1 or higher to run a Kafka Streams application version 0.10.1 or higher;
-        On-disk message format must be 0.10 or higher to run a Kafka Streams application version 1.0 or higher.
+        To run a Kafka Streams application version 2.2.1, 2.3.0, or higher a broker version 0.11.0 or higher is required
+        and the on-disk message format must be 0.11 or higher.
+        Brokers must be on version 0.10.1 or higher to run a Kafka Streams application version 0.10.1 to 2.2.0.
+        Additionally, on-disk message format must be 0.10 or higher to run a Kafka Streams application version 1.0 to 2.2.0.
         For Kafka Streams 0.10.0, broker version 0.10.0 or higher is required.
     </p>
 
@@ -139,6 +141,12 @@ <h3><a id="streams_api_changes_230" href="#streams_api_changes_230">Streams API
         For more details please read <a href="https://issues.apache.org/jira/browse/KAFKA-8215">KAFKA-8215</a>.
     </p>
 
+    <h3><a id="streams_notable_changes_221" href="#streams_api_changes_221">Notable changes in Kafka Streams 2.2.1</a></h3>
+    <p>
+        As of Kafka Streams 2.2.1 a message format 0.11 or higher is required;
+        this implies that brokers must be on version 0.11.0 or higher.
+    </p>
+
     <h3><a id="streams_api_changes_220" href="#streams_api_changes_220">Streams API changes in 2.2.0</a></h3>
     <p>
         We've simplified the <code>KafkaStreams#state</code> transition diagram during the starting up phase a bit in 2.2.0: in older versions the state will transit from <code>CREATED</code> to <code>RUNNING</code>, and then to <code>REBALANCING</code> to get the first

docs/upgrade.html

@@ -99,6 +99,7 @@ <h5><a id="upgrade_230_notable" href="#upgrade_230_notable">Notable changes in 2
     <li> Kafka Streams DSL switches its used store types. While this change is mainly transparent to users, there are some corner cases that may require code changes.
         See the <a href="/{{version}}/documentation/streams/upgrade-guide#streams_api_changes_230">Kafka Streams upgrade section</a> for more details.
     </li>
+    <li>Kafka Streams 2.3.0 requires 0.11 message format or higher and does not work with older message format.</li>
 </ul>
 
 <h4><a id="upgrade_2_2_0" href="#upgrade_2_2_0">Upgrading from 0.8.x, 0.9.x, 0.10.0.x, 0.10.1.x, 0.10.2.x, 0.11.0.x, 1.0.x, 1.1.x, 2.0.x or 2.1.x to 2.2.0</a></h4>
@@ -143,6 +144,11 @@ <h4><a id="upgrade_2_2_0" href="#upgrade_2_2_0">Upgrading from 0.8.x, 0.9.x, 0.1
     </li>
 </ol>
 
+<h5><a id="upgrade_221_notable" href="#upgrade_221_notable">Notable changes in 2.2.1</a></h5>
+<ul>
+    <li>Kafka Streams 2.2.1 requires 0.11 message format or higher and does not work with older message format.</li>
+</ul>
+
 <h5><a id="upgrade_220_notable" href="#upgrade_220_notable">Notable changes in 2.2.0</a></h5>
 <ul>
     <li>The default consumer group id has been changed from the empty string (<code>""</code>) to <code>null</code>. Consumers who use the new default group id will not be able to subscribe to topics,