docs: Fix incorrect verb form in Block manager section Update stack.md (#541)

Author: voronor

learn/stack.md

@@ -62,7 +62,7 @@ The [mempool](https://github.com/rollkit/rollkit/tree/main/mempool) is inspired
 
 ### Block manager
 
-The [block manager](https://github.com/rollkit/rollkit/tree/main/block) contains routines `AggregationLoop`, `RetrieveLoop`, and `SyncLoop` that communicate through Go channels. These Go routines are ran when a Rollkit node starts up (`OnStart`). Only the sequencer nodes run `AggregationLoop` which controls the frequency of block production for a rollup with a timer as per the `BlockTime` in `BlockManager`.
+The [block manager](https://github.com/rollkit/rollkit/tree/main/block) contains routines `AggregationLoop`, `RetrieveLoop`, and `SyncLoop` that communicate through Go channels. These Go routines are run when a Rollkit node starts up (`OnStart`). Only the sequencer nodes run `AggregationLoop` which controls the frequency of block production for a rollup with a timer as per the `BlockTime` in `BlockManager`.
 
 All nodes run `SyncLoop` which looks for the following operations: