[CXX] BSON Binary Vector Subtype Support (#131)

* bson vector release note

* fix link

* NR feedback

* link

* format

* format

Author: rachel-mack

source/whats-new.txt

@@ -27,6 +27,20 @@ Learn what's new in:
 * :ref:`Version 3.10 <version-3.10>`
 * :ref:`Version 3.9 <version-3.9>`
 
+.. _version-4.1:
+
+What's New in 4.1
+-----------------
+
+The v4.1 driver release includes the following new features:
+
+- Adds support for the BSON Binary Vector type.  
+  
+  For more information, see the following resources:
+
+  - :manual:`Binary Data BSON Types </reference/bson-types/#binary-data>` in the {+mdb-server+} manual
+  - :github:`BSON Binary Vector </mongodb/mongo-cxx-driver/blob/master/examples/bsoncxx/bson_binary_vector.cpp>` usage example on GitHub
+
 .. _version-4.0:
 
 What's New in 4.0