Update 16.10 documentation for failing migration

What does this MR do and why?

An open bug has seen at least four tickets opened up with Customer Support where migrations fail to complete when upgrading to 16.10. As a first iteration, this is a basic documentation addition that provides an acknowledgement of the bug, and re-structures the workaround that has been confirmed to resolve the problem for applicable users.

A fix is intended to be rolled out in this merge request. The documentation can be updated to indicate to, where possible, upgrade to the later patch version of 16.10.x, or 16.11, where this is resolved without user interaction.

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