docs: add more recommendataions to GarbageCollectionPeriod

We're trying to delete less than 1% of data in the default configuration for
mainnet, so it looks like this:

    2025-01-14T15:51:39.449+0300    INFO    finished MPT garbage collection {"removed": 221115, "kept": 71236766, "time": "5m40.323822085s"}

Spending this much time for this low gain every 10K blocks is far from being
optimal.

Signed-off-by: Roman Khimov <roman@nspcc.ru>

docs/node-configuration.md

@@ -18,7 +18,7 @@ node-related settings described in the table below.
 | --- | --- | --- | --- |
 | DBConfiguration | [DB Configuration](#DB-Configuration) |  | Describes configuration for database. See the [DB Configuration](#DB-Configuration) section for details. |
 | LogLevel | `string` | "info" | Minimal logged messages level (can be "debug", "info", "warn", "error", "dpanic", "panic" or "fatal"). |
-| GarbageCollectionPeriod | `uint32` | 10000 | Controls MPT garbage collection interval (in blocks) for configurations with `RemoveUntraceableBlocks` enabled and `KeepOnlyLatestState` disabled. In this mode the node stores a number of MPT trees (corresponding to `MaxTraceableBlocks` and `StateSyncInterval`), but the DB needs to be clean from old entries from time to time. Doing it too often will cause too much processing overhead, doing it too rarely will leave more useless data in the DB. |
+| GarbageCollectionPeriod | `uint32` | 10000 | Controls MPT garbage collection interval (in blocks) for configurations with `RemoveUntraceableBlocks` enabled and `KeepOnlyLatestState` disabled. In this mode the node stores a number of MPT trees (corresponding to `MaxTraceableBlocks` and `StateSyncInterval`), but the DB needs to be clean from old entries from time to time. Doing it too often will cause too much processing overhead (it requires going through the whole DB which can take minutes), doing it too rarely will leave more useless data in the DB. Always compare this to `MaxTraceableBlocks`, values lower than 10% of it are likely too low, values higher than 50% are likely to leave more garbage than is possible to collect. The default value is more aligned with NeoFS networks that have low MTB values, but for N3 mainnet it's too low. |
 | KeepOnlyLatestState | `bool` | `false` | Specifies if MPT should only store the latest state (or a set of latest states, see `P2PStateExchangeExtensions` section in the ProtocolConfiguration for details). If true, DB size will be smaller, but older roots won't be accessible. This value should remain the same for the same database. |  |
 | LogPath | `string` | "", so only console logging | File path where to store node logs. |
 | NeoFSBlockFetcher | [NeoFS BlockFetcher Configuration](#NeoFS-BlockFetcher-Configuration) | | NeoFS BlockFetcher module configuration. See the [NeoFS BlockFetcher Configuration](#NeoFS-BlockFetcher-Configuration) section for details. |