Update billing.md - Clarifications on data lake billing

Author: DaniHalfin

articles/sentinel/billing.md

@@ -72,6 +72,7 @@ For more information, see [Microsoft Sentinel data lake](datalake/sentinel-lake-
 The data lake tier incurs charges based on usage of various data like capabilities. 
 - **Data lake ingestion** charges are incurred per GB of data ingested for tables in Lake only mode.
 - **Data lake storage** charges are incurred per GB per month for any data stored beyond the interactive retention period or in Lake only mode.
+- **Data processing** charges are incurred per GB processed to transform data. This would bill for the [data collection rules](data-transformation.md#dcr-support-in-microsoft-sentinel) capability over data ingested into data lake.
 - **Data lake query** charges are incurred per GB of data analyzed using data lake exploration KQL queries, KQL jobs, or Search.
 - **Advanced data insights** charges are incurred per compute hour used when using data lake exploration notebook sessions or running data lake exploration notebook jobs. Compute hours are calculated by multiplying the number of cores in the pool selected for the notebook with the amount of time a session was active or a job was running.
 
@@ -87,6 +88,8 @@ For customers that haven't onboarded to the Microsoft Sentinel data lake and are
 
 The following are considerations that are going to apply during preview:
 - Data lake ingestion includes 30-days of retention for data ingested directly into the lake.
+- Entra asset data retention is offered free of charge.
+- Data processing of data ingested into data lake is offered free of charge.
 - While long-term retention billing will transition to the data lake storage meter for existing customers, data in long-term retention will initially only be accessible through **Microsoft Sentinel > Data lake exploration > Search & restore**.
 - Charges for data lake usage will show in part under a workspace resource and in part under a SentinelPlatformServices resource.
 - Data written to analytics tier using jobs will be charged through the analytics ingestion meter.