update config.md file

Author: pthmas

docs/learn/config.md

@@ -17,6 +17,7 @@ This document provides a comprehensive reference for all configuration options a
   - [Maximum Pending Blocks](#maximum-pending-blocks)
   - [Lazy Mode (Lazy Aggregator)](#lazy-mode-lazy-aggregator)
   - [Lazy Block Interval](#lazy-block-interval)
+  - [Pruning (Height-Based Pruning)](#pruning-height-based-pruning)
 - [Data Availability Configuration (`da`)](#data-availability-configuration-da)
   - [DA Service Address](#da-service-address)
   - [DA Authentication Token](#da-authentication-token)
@@ -279,6 +280,40 @@ _Example:_ `--rollkit.node.lazy_block_interval 1m`
 _Default:_ `"30s"`
 _Constant:_ `FlagLazyBlockTime`
 
+### Pruning (Height-Based Pruning)
+
+**Description:**
+Controls height-based pruning of stored block data (headers, data, signatures, and index) from the local store. When pruning is enabled, the node periodically deletes old blocks while keeping a recent window of history. When disabled, the node keeps all blocks (archive mode).
+
+**YAML:**
+
+```yaml
+node:
+  pruning_enabled: true
+  pruning_keep_recent: 100000
+  pruning_interval: 1000
+```
+
+**Command-line Flags:**
+
+- `--evnode.node.pruning_enabled` (boolean)
+  - _Description:_ Enable height-based pruning of stored block data. When disabled, all blocks are kept (archive mode).
+- `--evnode.node.pruning_keep_recent <uint64>`
+  - _Description:_ Number of most recent blocks to retain when pruning is enabled. Must be > 0 when pruning is enabled; set `pruning_enabled=false` to keep all blocks.
+- `--evnode.node.pruning_interval <uint64>`
+  - _Description:_ Run pruning every N blocks. Must be >= 1 when pruning is enabled.
+
+_Defaults:_
+
+```yaml
+node:
+  pruning_enabled: false
+  pruning_keep_recent: 0
+  pruning_interval: 0
+```
+
+_Constants:_ `FlagNodePruningEnabled`, `FlagNodePruningKeepRecent`, `FlagNodePruningInterval`
+
 ## Data Availability Configuration (`da`)
 
 Parameters for connecting and interacting with the Data Availability (DA) layer, which Evolve uses to publish block data.