MINOR: Update KRaft cluster upgrade documentation for 3.4
Reviewers: Ismael Juma
</li>
</ol>
+<h4><a id="upgrade_kraft_3_4_0" href="#upgrade_kraft_3_4_0">Upgrading a KRaft-based cluster to 3.4.0 from any version 3.0.x through 3.3.x</a></h4>
+
+ <p><b>If you are upgrading from a version prior to 3.3.0, please see the note below. Once you have changed the metadata.version to the latest version, it will not be possible to downgrade to a version prior to 3.3-IV0.</b></p>
+
+ <p><b>For a rolling upgrade:</b></p>
+
+ <ol>
+ <li>Upgrade the brokers one at a time: shut down the broker, update the code, and restart it. Once you have done so, the
+ brokers will be running the latest version and you can verify that the cluster's behavior and performance meets expectations.
+ </li>
+ <li>Once the cluster's behavior and performance has been verified, bump the metadata.version by running
+ <code>
+ ./bin/kafka-features.sh upgrade --metadata 3.4
+ </code>
+ </li>
+ <li>Note that the cluster metadata version cannot be downgraded to a pre-production 3.0.x, 3.1.x, or 3.2.x version once it has been upgraded.
+ However, it is possible to downgrade to production versions such as 3.3-IV0, 3.3-IV1, etc.</li>
+ </ol>
+
<h4><a id="upgrade_3_3_1" href="#upgrade_3_3_1">Upgrading to 3.3.1 from any version 0.8.x through 3.2.x</a></h4>
<p><b>If you are upgrading from a version prior to 2.1.x, please see the note below about the change to the schema used to store consumer offsets.
</li>
</ol>
-<h4><a id="upgrade_3_3_1" href="#upgrade_3_3_1">Upgrading a KRaft-based cluster to 3.3.1 from any version 3.0.x through 3.2.x</a></h4>
+<h4><a id="upgrade_kraft_3_3_1" href="#upgrade_kraft_3_3_1">Upgrading a KRaft-based cluster to 3.3.1 from any version 3.0.x through 3.2.x</a></h4>
<p><b>If you are upgrading from a version prior to 3.3.1, please see the note below. Once you have changed the metadata.version to the latest version, it will not be possible to downgrade to a version prior to 3.3-IV0.</b></p>
