There are 2 issues that should be covered in the product docs:
1. Since 4.12 the operand Image field in the NFD CR is mandatory. In case the NFD operator is deployed via OLM, this field is filled up by OLM automatically. In case the CR is applied via other code/manually, it must be set explicitly
2. When updating NFD operator from 4.12 to 4.13 and the TopologyUpdater is enabled, the Topology pod will crush once the update is completed. This is due to the changes in the input parameters of the Topology Updater. This does not affect already procurred labels, and all that is need to be done is to apply an 4.13 NFD CR. 

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