Add BQ dataset's partition expiry

add debugging information about partition expiration which can be set on a dataset level for BQ

Author: muhammadatifjav

src/connections/storage/catalog/bigquery/index.md

@@ -220,4 +220,10 @@ a need for streaming data into BigQuery, [contact Segment support](https://segme
 
 ### I see duplicates in my tables.
 
-This behavior is expected. Segment only de-duplicates data in your views. Refer to the [schema section](#schema) for more details.
+This behavior is expected. Segment only de-duplicates data in your views. Refer to the [schema section](#schema) for more details.
+
+### BigQuery Default Partition Expiration
+
+If you notice that your BigQuery data is getting deleted after a specific period of time, then it might be due to a [dataset's default table expiration](https://cloud.google.com/bigquery/docs/updating-datasets#partition-expiration) in BigQuery that sets a 90-day (or similar) expiration on all partitioned tables that are created. 
+
+However, you can safely remove these expirations from the tables/dataset and change them to ‘Never’, and change the dataset's default table expiration as needed. We will then be able to run a backfill for you to send all the historical data to your warehouse.