DOCS-1014 add cursor.objsLeftInBatch

Author: kay-kim

source/reference/method/cursor.objsLeftInBatch.txt

@@ -0,0 +1,16 @@
+========================
+cursor.objsLeftInBatch()
+========================
+
+.. default-domain:: mongodb
+
+.. method:: cursor.objsLeftInBatch()
+
+   The :method:`cursor.objsLeftInBatch()` returns the number of
+   documents remaining in the current batch.
+
+   The MongoDB instance returns its response in batches. The retrieval
+   of all the documents from a cursor may require multiple batch
+   responses from the MongoDB instance. When there are no more
+   documents remaining in the current batch, the cursor will retrieve
+   another batch to get more documents.