add doc

models/docs/universal.md

@@ -75,6 +75,10 @@ String representation of the run id for a given DAG in Airflow. Takes the form o
 The start date for the batch interval. When taken with the date in the batch_id, the date represents the interval of ledgers processed. The batch run date can be seen as a proxy of closed_at for a ledger.
 {% enddocs %}
 
+{% docs batch_insert_ts %}
+The timestamp in UTC when a batch of records was inserted into the database. This field can help identify if a batch executed in real time or as part of a backfill. The timestamp should not be used during ad hoc analysis and is useful for data engineering purposes.
+{% enddocs %}
+
 {% docs address %}
 The address of the account. The address is the account's public key encoded in base32. All account addresses start with a `G`
 {% enddocs %}