MINOR: update kraft dynamic voter set doc (#20401)

Update the KRaft dynamic voter set documentation. In Kafka 4.1, we
introduced a powerful new feature that enables seamless migration from a
static voter set to a dynamic voter set.

Reviewers: Ken Huang <[email protected]>, TengYao Chi
<[email protected]>, Chia-Ping Tsai <[email protected]>

Author: brandboat

docs/ops.html

@@ -4106,11 +4106,9 @@ <h5 class="anchor-heading"><a id="static_versus_dynamic_kraft_quorums" class="an
 
 <pre><code class="language-bash">
   $ bin/kafka-storage.sh format -t KAFKA_CLUSTER_ID --feature kraft.version=1 -c controller.properties
-  Cannot set kraft.version to 1 unless KIP-853 configuration is present. Try removing the --feature flag for kraft.version.
 </code></pre><p>
 
-  Note: Currently it is <b>not</b> possible to convert clusters using a static controller quorum to
-  use a dynamic controller quorum. This function will be supported in the future release.
+  Note: To migrate from static voter set to dynamic voter set, please refer to the <a href="#kraft_upgrade">Upgrade</a> section.
 
   <h5 class="anchor-heading"><a id="kraft_reconfig_add" class="anchor-link"></a><a href="#kraft_reconfig_add">Add New Controller</a></h5>
   If a dynamic controller cluster already exists, it can be expanded by first provisioning a new controller using the <a href="#kraft_nodes_observers">kafka-storage.sh tool</a> and starting the controller.