Fixed statement in query restrictions

The restrictions on RowBatcher for e.g. groupBy/limit/orderBy don't apply to the Spark connector. The connector will push those down to MarkLogic, but if more than 1 call is made to MarkLogic, Spark will apply them as well, thus avoiding the problem that RowBatcher has where those calls only get applied to each batch and not the entire set of matching rows.

Author: rjrudin

docs/reading.md

@@ -48,11 +48,21 @@ query expansion via [a thesaurus](https://docs.marklogic.com/guide/search-dev/th
 
 ## Optic query requirements
 
-As of the 2.0 release of the connector, the Optic query must use the 
-[op.fromView](https://docs.marklogic.com/op.fromView) accessor function. The query must also adhere to the 
-restrictions that the 
-[RowBatcher in the Data Movement SDK](https://github.com/marklogic/java-client-api/wiki/Row-Batcher#building-a-plan-for-exporting-the-view)
-adheres to as well. 
+As of the 2.0.0 release of the connector, the Optic query must use the 
+[op.fromView](https://docs.marklogic.com/op.fromView) accessor function. Future releases of both the connector and 
+MarkLogic will strive to relax this requirement. 
+
+In addition, calls to `groupBy`, `orderBy`, `limit`, and `offset` should be performed via Spark instead of within 
+the initial Optic query. A key benefit of Spark and the MarkLogic connector is the ability to execute the query in 
+parallel via multiple Spark partitions. The aforementioned calls, if made in the Optic query, may not produce the 
+expected results if more than one Spark partition is used or if more than one request is made to MarkLogic. The 
+equivalent Spark operations should be called instead, or the connector should be configured to make a single request 
+to MarkLogic. See the "Pushing down operations" and "Tuning performance" sections below for more information.
+
+Finally, the query must adhere to the handful of limitations imposed by the  
+[Optic Query DSL](https://docs.marklogic.com/guide/app-dev/OpticAPI#id_46710). A good practice in validating a 
+query is to run it in your [MarkLogic server's qconsole tool](https://docs.marklogic.com/guide/qconsole) in a buffer 
+with a query type of "Optic DSL". 
 
 ## Schema inference