Document the new flag --disable-consumer-sync in the konnect section

[mlavacca]

Problem Statement

#6313 added a new --disable-consumer-sync flag to disable synchronization of consumers to connect. Such a flag can be useful in case users have many consumers in their setup, as this can cause slowdowns in the sync phase. We need to add a section in the documentation on how to use such a flag and in which context can be useful.

Acceptance Criteria

• a new section explaining the --disable-consumer-sync flag is added in the connect guide.