Release notes in the Alpakka Kafka documentation

Alpakka Kafka core

• Emit offset batches on timer #1160 by @jyates
• Do not commit offsets for unassigned partitions #1123 by @jyates

Alpakka Kafka Akka Cluster Sharding

• Use bulk update API for shard allocation #1139 by @chbatey
• Don't use ctx.log in KafkaClusterSharding #1138 by @chbatey

Alpakka Kafka Testkit

• Deprecate embedded kafka support #1136 by @seglo
• Replace embedded kafka with schema registry with testcontainers #1135 by @seglo
• Add produce consume check to KafkaContainerCluster #1131 by @seglo

Updates

• mockito-core 2.28.2 (was 2.24.5) #1151 by @scala-steward
• scala-collection-compat 2.1.6 (was 2.1.2) #1152 by @scala-steward
• jul-to-slf4j, log4j-over-slf4j 1.7.30 (was 1.7.26) #1155 by @scala-steward
• embedded-kafka 2.4.1.1 (was 2.4.1) #1147 by @scala-steward
• protobuf-java 3.12.2 (was 3.11.4) #1142 by @scala-steward
• sbt 1.3.13 (was 1.3.9) #1153 by @scala-steward
• akka-stream-alpakka-csv 2.0.1 (was 2.0.0) #1143 by @scala-steward