docs: add link for block status info (#415)

Author: sarahschwartz

content/20.zksync-protocol/10.api/10.conventions.md

@@ -57,6 +57,11 @@ The following options are possible for the defaultBlock parameter:
 - String "finalized" - for the latest finalized block
 - String "pending" - for the pending state/transactions
 
+::callout{icon="i-heroicons-information-circle" color="blue"}
+[Learn more](https://www.alchemy.com/docs/reference/ethereum-developer-guide-to-the-merge#what-are-safe-and-finalized)
+about the difference between "safe" and "finalized".
+::
+
 ## Batching JSON-RPC Requests
 
 JSON-RPC requests can be batched together.