MINOR: Add missing MirrorMaker2 metrics to docs (#18691)

Reviewers: Mickael Maison <[email protected]>
Co-authored-by: u0184996 <[email protected]>

docs/ops.html

@@ -1035,6 +1035,7 @@ <h4 class="anchor-heading"><a id="georeplication-monitoring" class="anchor-link"
 
 <pre><code class="language-text"># MBean: kafka.connect.mirror:type=MirrorSourceConnector,target=([-.w]+),topic=([-.w]+),partition=([0-9]+)
 record-count            # number of records replicated source -> target
+record-rate             # average number of records/sec in replicated records
 record-age-ms           # age of records when they are replicated
 record-age-ms-min
 record-age-ms-max
@@ -1044,8 +1045,9 @@ <h4 class="anchor-heading"><a id="georeplication-monitoring" class="anchor-link"
 replication-latency-ms-max
 replication-latency-ms-avg
 byte-rate               # average number of bytes/sec in replicated records
+byte-count              # number of bytes replicated source -> target
 
-# MBean: kafka.connect.mirror:type=MirrorCheckpointConnector,source=([-.w]+),target=([-.w]+)
+# MBean: kafka.connect.mirror:type=MirrorCheckpointConnector,source=([-.w]+),target=([-.w]+),group=([-.w]+),topic=([-.w]+),partition=([0-9]+)
 
 checkpoint-latency-ms   # time it takes to replicate consumer offsets
 checkpoint-latency-ms-min