Merge pull request #3203 from nspcc-dev/doc-upd

docs: adjust ValidatorsHistory documentation

docs/node-configuration.md

@@ -345,7 +345,7 @@ protocol-related settings described in the table below.
 | StateSyncInterval | `int` | `40000` | The number of blocks between state heights available for MPT state data synchronization. | `P2PStateExchangeExtensions` should be enabled to use this setting. |
 | TimePerBlock | `Duration` | `15s` | Minimal (and targeted for) time interval between blocks. Must be an integer number of milliseconds. |
 | ValidatorsCount | `uint32` | `0` | Number of validators set for the whole network lifetime, can't be set if `ValidatorsHistory` setting is used. |
-| ValidatorsHistory | map[uint32]uint32 | none | Number of consensus nodes to use after given height (see `CommitteeHistory` also). Heights where the change occurs must be divisible by the number of committee members at that height. Can't be used with `ValidatorsCount` not equal to zero. |
+| ValidatorsHistory | map[uint32]uint32 | none | Number of consensus nodes to use after given height (see `CommitteeHistory` also). Heights where the change occurs must be divisible by the number of committee members at that height. Can't be used with `ValidatorsCount` not equal to zero. Initial validators count for genesis block must always be specified. |
 | VerifyTransactions | `bool` | `false` | Denotes whether to verify transactions in the received blocks. |
 
 ### Genesis Configuration