KAFKA-14709: Move content in connect/mirror/README.md to the docs

[tinaselenge]

Most of the contents in the README.md was already covered in the docs therefore only had to add the section for Exactly Once support.

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)

[machi1990]

one minor suggestion, otherwise it looks good to me.

[showuon]

@tinaselenge , thanks for the PR, left a comment.

[showuon]

I don't see this Shared configuration is mentioned in the doc. Could you check it again?

[tinaselenge]

I believe this is already included in the doc.

kafka/docs/ops.html

Line 874 in f275ed8

MirrorMaker processes share configuration via their target Kafka clusters. This behavior may cause conflicts when configurations differ among MirrorMaker processes that operate against the same target cluster.

[showuon]

Ah, you're right. It's just not having the same title. Thanks.

[showuon]

LGTM!

[showuon]

Ah, you're right. It's just not having the same title. Thanks.

[showuon]

Re-triggering the CI: https://ci-builds.apache.org/job/Kafka/job/kafka-pr/job/PR-13650/3/

[showuon]

Failed tests are unrelated:

    Build / JDK 11 and Scala 2.13 / org.apache.kafka.connect.mirror.integration.MirrorConnectorsIntegrationSSLTest.testSyncTopicConfigs()
    Build / JDK 11 and Scala 2.13 / kafka.admin.DescribeConsumerGroupTest.testDescribeOffsetsOfExistingGroupWithNoMembers()
    Build / JDK 11 and Scala 2.13 / kafka.zk.ZkMigrationIntegrationTest.[1] Type=ZK, Name=testNewAndChangedTopicsInDualWrite, MetadataVersion=3.4-IV0, Security=PLAINTEXT
    Build / JDK 8 and Scala 2.12 / org.apache.kafka.connect.mirror.integration.DedicatedMirrorIntegrationTest.testMultiNodeCluster()
    Build / JDK 8 and Scala 2.12 / kafka.api.ConsumerBounceTest.testClose()
    Build / JDK 8 and Scala 2.12 / kafka.api.PlaintextConsumerTest.testMaxPollIntervalMs()
    Build / JDK 8 and Scala 2.12 / org.apache.kafka.streams.integration.StoreUpgradeIntegrationTest.shouldMigratePersistentKeyValueStoreToTimestampedKeyValueStoreUsingPapi