[srvls] Document integration of Managed Kafka Connections with Kafka source

Dev Epic: https://issues.redhat.com/browse/ODC-5399

From eng issue:

Improved integration of Managed Services with Kafka source

1. In topology only for KafkaSouce, a Managed Kafka Connection (MKC) will be a valid target (like connector) i,e ability to create a connector only on Kafka Source with MKC as valid target and on dropping on MKC should update KafkaSource with SASL secrets , TLS enabled and bootstrap server (will be handling this with logic is UI as SBR is not meant for it, just as we update sink for any sources currently).
2. In the Kafka Source creation form, show type ahead with bootstrap server from MKC if the project has MKC and user has access to them