Cosmos DB: Adding note about maxitemCount (Azure#28447)

sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/models/ChangeFeedProcessorOptions.java

@@ -190,6 +190,13 @@ public int getMaxItemCount() {
 
     /**
      * Sets the maximum number of items to be returned in the enumeration operation.
+     * <p>
+     * NOTE: This is just a hint to the server which can return less or more items per page.
+     * If operations in the container are performed through stored procedures or transactional batch,
+     * <a href="https://docs.microsoft.com/azure/cosmos-db/sql/stored-procedures-triggers-udfs#transactions">transaction
+     * scope</a> is preserved when reading items from the Change Feed.
+     * As a result, the number of items received could be higher than the specified value so that the items changed
+     * by the same transaction are returned as part of one atomic batch.
      *
      * @param maxItemCount the maximum number of items to be returned in the enumeration operation.
      * @return the current ChangeFeedProcessorOptions instance.