add link ref

Author: mongoKart

source/data-formats/bson.txt

@@ -117,6 +117,8 @@ The following example reads the sample BSON document from ``file.bson``:
 
       {"address": {"street": "Pizza St", "zipcode": "10003"}, "coord": [-73.982419, 41.579505], "cuisine": "Pizza", "name": "Mongo's Pizza"}
 
+.. _pymongo-bson-raw:
+
 Work with Raw BSON Data
 -----------------------