fix(docs): add FAQ entry about minimum history for Data Availability Layer (#503)

Author: fassko

docs/fassets/guides/5-faq.mdx

@@ -51,3 +51,8 @@ Yes, for an agent to stay operational, it must run continuously.
 Do not restart the agent, as this may result in double payments.
 The current solution is duplicating the database and launching a new agent instance.
 You should monitor your database closely and, if access is lost, remove the agent from the available list, self-close FAssets, and backup agent keys.
+
+### Is there a minimum history needed in the Data Availability Layer for agents?
+
+No minimum history is required; it can be set to the latest block.
+You need to start the [Data Availability Layer](/fdc/overview#data-availability-layer) before you can participate as an FAsset agent.