DOCSP-15559 Document ADL busy error message (#152)

* DOCSP-15559 Document ADL busy error message

* DOCSP-15559 updates for review feedback

Author: kanchana-mongodb

source/query/query-data-lake.txt

@@ -374,6 +374,19 @@ federated queries, {+dl+} combines data from your |service| cluster,
 |s3| bucket, and |http| store in virtual databases and collections and 
 returns a union of data in the results. 
 
+.. _query-troubleshooting:
+
+Toubleshooting 
+--------------
+
+**Error:** We are currently experiencing increased query processing 
+wait times for {+adl+}. Our Engineering team is investigating. Normal 
+service will resume shortly, please try again.
+
+{+adl+} returns this error only when {+adl+} can't execute queries 
+because of resource contention. We recommend that you run your queries 
+again.
+
 .. toctree::
    :titlesonly:
    :hidden: