Geo: Document need to update replicator_classes

What does this MR do?

From #227693 (comment 377326449):

I have unblocked !35443 (merged) by hard-coding the list of replicator classes. It's really not that bad for now. If that gets merged, then I'll update the framework doc to include adding your replicator to that list.

• Update framework document

Related issues

Part of #227693

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