f - Explain why block events need to be sent to ChannelManager and ChainMonitor

Author: jkczyz

docs/blockdata.md

@@ -42,7 +42,8 @@ At this point, LDK needs to be fed chain data of interest so that it can respond
 accordingly. It supports receiving either full blocks or pre-filtered blocks.
 Block data can sourced from anywhere, but it is your responsibility to ensure
 that the necessary `block_connected` and `block_disconnected` methods are called
-on `ChannelManager` and `ChainMonitor`.
+on `ChannelManager` and `ChainMonitor`. This allows them to update channel state
+and respond to on-chain events, respectively.
 
 LDK comes with a `lightning-block-sync` utility that handles polling a block
 source for the best chain tip, detecting chain forks, and notifying listeners