Update the check metadata consistency documentation

• Review the public documentation of the inconsistencies already uncovered by checkMetadataConsistency
• Cross-check them with the new ones that will be added as part of the Authoritative Shards program
• Including written details about exactly what each check does and the error/output that it will produce. These details should ideally be done for each of the existing checks, but as an exit criteria for this project it will be acceptable to do them only for the new checks.